Jean Bureau


Figure 1By Jacques Grignon (XVIIe s.) – Ambroise Tardieu, Dictionnaire iconographique des Parisiens, Herment, 1885., Public Domain,


Early History of Cannon

One may wonder why the English, who had enjoyed spectacular success at the Battles of Agincourt and Crecy, were forced out of most of their continental holdings to bring an end to the Hundred Years War. (8) French advances in artillery development provide some of the answer. (8) Cannons first seen use in the Hundred Years War at Crecy. (4) Edward III was very keen on them, and his Ribaldis shot large arrows and grapeshot to mow down enemy infantry. (4) He amassed a pretty substantial collection of artillery and certainly had far more than the French. (4) But innovation in cannon at this period was in the Ottoman Empire. (4) Having been repulsed from Constantinople in 1396 by cannon, the Ottoman Caliphs spent lavishly on bigger and better cannon to level the place at their next attempt in 1422. (4) This didn’t work, but by the time they came back in 1453 they had dozens of them including the awesome ‘Basilica’ 27 feet long and able to hurl a 600lb shot over a mile. (4) It was pretty inaccurate though, and managed to miss the entire city. (4) Henry IV didn’t even take his guns to France, though Henry V did and took Harfleur with them and they were present at Agincourt, though played little part compared to the longbows. (4) They did see use throughout the rest of his French campaigns. (4) The English began besieging Guise in January of 1424, but did not enter the town until February of 1425. (13) In all the cases cited above, the chroniclers give lack of supplies as the primary reason for the eventual surrender of the besieged. (13) Around the middle of the 1420s, however, we begin to hear of garrisons surrendering, not because of hunger, but because the besiegers’ guns have rendered their position indefensible. (13) According to the French chroniclers, this was the case at Le Mans, Sainte-Suzanne, Mayenne-la-Juhez, Montmiral, and Gallardon, all in 1423. (13) At Sainte-Suzanne, then the second largest town of Maine, “the count of Salisbury had nine large bombards and many large cannon and fowlers [lighter cannon] sited and set up. (13) These bombards and cannons, after eight or ten days, began to fire incessantly, day and night, so that they beat down the walls of the said town from more than a bow-shot away. (13) The following year the Duke of Bedford besieged Gaillon, “a very strong place,” and “it was battered so effectively, that the garrison surrendered on having their lives spared. (13) In Bohemia, too, we first hear in the early 1420s of “large cannon, with which one might knock down strong walls”. (13)

Bureau family background

Jean Bureau was born (1,2) at Semoine (7,11) in Champagne (1,2) in (9) OR in about 1390 (1,7) Jean and Gaspard Bureau were sons of Simon Bureau. (1,5) the Younger (Le Jeune) (5) a merchant from Paris, and his wife Hélène. (5,11) Gaspard was their third son (5) born in about (1) 1393 (1,2) John was the second son. (7) In 1420 (11) he moved to Paris (2,7) and studied law (7,9) OR to work as a lawyer. (11) and then worked as a lawyer in Paris. (9,11) He worked for the English government (2) as a commissioner, (9) a legal official at the Châtelet. (7,11) OR under the Lancastrian administration in Normandy established by English King Henry V. (12) Bureau immersed himself in the study of artillery. (12) Thanks to his sharp mind and good education, he easily grasped the revolutionary developments in gunpowder and gun manufacture and the implications they held for land warfare. (12) Up to this point the use of gunpowder artillery had not yet achieved complete triumph over medieval fortifications. (13) As mentioned above, the siege of Guise in 1424 lasted over a year, and Ferte-Bernard managed to hold out against Salisbury for several months in the same year. (13) In 1429 the English had to spend six months starving out the castle of Torcy; the French garrison of Chateau Gaillard had once again to be starved out that year; the siege of Laigny-sur-Marne took over five months in 1432; and as late as 1440 Harfleur was able to resist an English siege for over three months. (13) Each of these places, however, was exceptionally strong, and each was attacked by a relatively weak English siege train. (13) During the period Paris was occupied by the English (2,7) under the command of the Duke of Bedford (7,9) after Henry V’s death in 1422. (12) Jean served as a gunner under John, Duke of Bedford, who led the English forces in France (12) For reasons that remain unclear, (12) in 1434 he left Paris and threw in his lot with Charles VII, (7,9) who had been crowned five years before in Reims. (12) He became an administrator for the French King, (7,12) as ‘Receiver Ordinary’ in Paris (7) in 1436 (11) OR ‘He left Paris’ (7,9)

The brothers enter the army

In the last decades of the Hundred Years’ War (1337-1453 CE) between France and England, artillery began to play an increasing role in warfare. (3) Bureau probably learned the artillery trade for its commercial potential. (11) Around 1424, (3) OR in 1436. (5) OR in 1434 (11) Jean and Gaspard Bureau joined the French army of Charles VII, and quickly asserted themselves as artillery experts. (3,11) The brothers quickly became the king’s most skilled artillery officers. (3) OR Gaspard was master of the accounts. (9) Jean was also appointed “Receiver of Paris” in 1436, and “Treasurer of France” in 1443. (11) By this time the powerful Burgundian artillery of the 1430s, on the other hand, could demolish the walls of most fortifications. (13) In 1430, the Burgundian siege train was able to “do so much damage to the walls of the castle [of Choisy] that the garrison capitulated” in a mere few days. (13) Similarly, at Avalon in 1433, the Burgundian artillery was “pointed against the gates and walls, and damaged them greatly, breaches being made in divers parts. (13) By 1437, even the English artillery was capable of leaving a stronghold with “a great part of the walls … thrown to the ground, so that it was in no way defensible. (13) Based on the above accounts, it seems fair to say that a revolution occurred in the art of war around the 1420s to 1430s, as gunpowder artillery overturned the centuries-old dominance of the defensive in siege warfare. (13) What was the nature of this revolution?

The Army reforms of Charles VII

Permanent Taxation

In the Middle Ages, the King of France was the head of an army comprised of his vassals. (10) In order to fund a military campaign, he had to gather the États généraux, an assembly which had the authority to decide whether or not to impose an extraordinary tax: the land tax. (10) Charles VII reformed this system. (10) Having obtained from local assemblies and states general or provincial taxes necessary for the financing of the war, Charles VII, with the help of Jacques Coeur, his great financier, managed to accustom his subjects to permanent taxation. (13) He gradually managed to convince the États Généraux to make the land tax permanent. (10) From around 1450 the States-General was no longer convened bringing an end to the consent which had been regarded as essential for ‘extraordinary’ taxation. (13) Permanent taxation was a monarchical right alien to the customary law according to which the King been required to live on his ordinary revenues, like a private person. (13)

The new army

Alongside his engineering advancements, there were equally important upgrades in the French army. (8) This included forming an army under direct royal control. (8) Fifteen captains, chosen based on their birth and their strengths, were made responsible for putting together a company of 100 lance units each. (10) The lance, which was a tactical unit, comprised four combatants: one unit leader, two archers and one coutilier in addition to two mounted auxiliaries. (10) By 1442 (8) Charles VII thus had a permanent army of 9,000 (10) OR approximately 15,000 (8) men who were paid in both times of war and peace. (10) – The Petite Ordonnance provided for the mortes-payes, which were lances, reduced to four members and assigned to the garrisons of strongholds. (10) With the new funding, Charles V promulgated a ruling on 26th May 1445 called the Grande Ordonnance de Louppy-le-Château, which established the foundations for a permanent army made of 15 companies at the exclusive service of the King. (10) The Franc-archers, created in 1448, were a militia of commoners. (10) Exempted from tax because of their military service, they were the reserve of the permanent army. (10) This army was under the direct command of their king, where before groups of fighting men had been under aristocratic direction. (8)

The technical improvements

Gaspard became an expert in ballistics and an inventor. (6) OR part of its financial administration as master of accounts, though later becoming clerk of the artillery then temporary master of artillery in 1442. (5) From 1437 onward, they used their expertise in artillery to aid in obtaining French victories. (3) OR It has been argued that gun design remained essentially stagnant until well into the fifteenth century, and that the most important advances were made after the artillery pioneers Jean and Gaspard Bureau became Treasurer and Master of Artillery of France, respectively, around 1440. (13) In fact, however, cannon developed steadily throughout the fourteenth century, and very rapidly in the early fifteenth. (13) Indeed, the developments in cannon design most critical for the Artillery Revolution appeared in the years 1400-1430. (13) Between 1400 and 1430, a whole series of interconnected innovations synergistically improved the power and efficiency of gun–powder artillery. (13)


At about the same time, a metallurgical innovation made the prodigious quantities of iron used in this process less expensive: the addition of limestone to the flux during the ore refinement process. (13) This increased the temperature necessary to make the slag free-running, so that it could only be used with developed blast furnaces, but it changed the structure of the slag from 2FeO.SiO2 to CaO.SiO2. (13) The two atoms of iron thus removed from each molecule of slag were no longer wasted, increasing the iron output from a given quantity of ore and making iron cheaper. (13)

Gunmaking skills

Meanwhile, as the manufacture of large iron cannon became more routine, the services of cannon-smiths grew more affordable. (13) The cost of cannon – which were priced in direct proportion to their weight – fell significantly (about a third) as a result of these changes. (13)

Design of guns

These developments included changes in the design and manufacture of the guns themselves, in loading methods, and in powder formulation. (13) But probably the most important of these involved the lengthening of gun barrels. (13) In 1400 most large bombards seem to have had barrel-lengths about equal to 1 – 1.5 times the diameter of the balls they shot. (13) By 1430 at the latest, the ratio of barrel length to ball diameter had grown to 3:1 or more. (13) In addition to increasing the accuracy of the shot (making it possible to concentrate the force of a large number of shots on a smaller area), this increased the amount of time over which the pressure of the exploding gunpowder accelerated the ball, and thus significantly increased the muzzle velocity of the shot. (13) Since the kinetic energy of the ball is a function of the square of the velocity, this meant a major increase in the effectiveness of the newer guns. (13) As contemporary gunners realized, it also meant an increase in range. (13) The lengthening of bombard barrels had an equally important indirect effect. (13)

Loading methods

In the early years of the fifteenth century, with the shorter-barreled bombards, a rather complex loading process had to be employed. (13) The gun crew filled the chamber with gunpowder for the rear three-fifths of its length. (13) The next fifth was left empty, and the last fifth filled by a soft wood plug cut to fit the chamber bore exactly. (13) Then the cannonball was fixed in place in the barrel with soft wood wedges. (13) Finally, to get the tightest possible seal (thus minimizing pressure loss to windage), wet mud mixed with straw was put in place and allowed to dry. (13) After the bombard had been fired, it had to be allowed to cool before more powder could be packed in. (13) This elaborate procedure so slowed down the firing process that one master gunner, who achieved the remarkable feat of firing his bombard three times in a single day and hitting different targets each time, was forced to make a pilgrimage from Metz to Rome, because it was thought that “he could only have been in league with the devil”. (13) Guns with longer barrels, however, ameliorated this problem. (13) Since the ball was under pressure from the expanding gas for a longer period of time, somewhat more gas loss due to windage could be allowed, and the wet loam seal dispensed with. (13) This, in turn, permitted more rapid firing. (13)


Barrels became cast, usually of bronze, instead of pieced together with iron rods, and breechloading was dropped in favor of muzzle loading, which was safer at the time. (8) Advances were made in gunpowder preparation to make it combust faster than before. (8) These upgrades resulted in higher than before pressures inside the barrel, thereby propelling the projectile farther and faster than with earlier firearms. (8) As guns of this sort became more common, there was an important change in the process used to manufacture them. (13) In the late fourteenth century, the barrels of large iron bombards were made either by forging a large iron plate into a cylinder, or by spiraling out a broad iron band, forming a cylinder in the same way that the coils of a spring do. (13) These methods, however, could not be scaled up past a certain point. (13) Innovations in casting helped create stronger barrels that were less likely to explode. (11) Sometime in the early fifteenth century, probably shortly before 1420, gunsmiths developed a new technique which made possible large guns with long barrels: they built up large iron guns out of long staves. (13) The staves were set in place around a cylindrical mandrel, then reinforced with bands of white hot iron, which were hammered down the cylinder like the hoops of a barrel. (13) The hoops shrank as they cooled, binding the staves tightly together. (13) Barrels could be conveniently elevated or depressed at the fulcrum of two rod-like extensions, the trunnions, cast as part of the barrel and balanced in slots on the carriage. (8) A cannon could be aimed left or right by simply picking up and shifting its trail. (8) The development of the hooped-staves method made it possible for even the largest iron cannon to have longer barrels, the adoption of which increased accuracy, power, and rate of fire. (13)


Advances in barrel casting were matched (8) by casting iron balls to be projectiles, in favour of carved stone. (8,9) Comparing the masses of volume to volume, a cast iron cannonball was heavier than its stone counterpart of the same diameter, hence, able to have greater force when impacting a castle wall. (8,9) They reorganised the field artillery. (5,7) They standardised its calibre and switched it from wrought iron to cast iron. (5) Louis-Napoleon Bonaparte said: “They began to employ, though in small numbers, iron balls instead of stone ones. (9) This made it possible for cannon to be smaller, and more powerful. (9) A projectile of the same weight occupying a smaller volume, would attain a higher velocity, because the gun, having a smaller calibre, created more force. (9) This harder ball did not break up like a stone one and so was able to penetrate masonry. (9)


The Bureau brothers benefitted from innovations in the manufacture of gunpowder in the late 1420s that generated a more potent powder that could fire projectiles at a much greater velocity, and did not require mixing in the field. (11) More or less simultaneously with these developments, an important change took place in a related area: the manufacture of gunpowder. (13) Around 1400, recipes for gunpowder began to appear which came quite close to the ideal proportions of saltpeter, sulphur, and charcoal. (13) But then, in the second decade of the century, it appears that the science of powdermaking took a retrograde step, moving significantly farther away from the “ideal” proportions. (13) Considering the high cost of gunpowder, it seems strange that gunners would adopt a less effective form of it. (13) The explanation of this seeming paradox lies in yet another new technique: the engraining or “corning” of powder. (13) Although there is evidence that the English may have employed this process as early as 1372, it seems that it did not come into use on the Continent until the around 1410; it was in almost universal use by 1420. (13) Corned powder, which was mixed together wet and then dried into kernels, had a number of advantages over the earlier “serpentine” powder, which was sifted together dry. (13) Sifted powder tended to separate into its component elements when transported, but corned powder was immune to this deterioration. (13) Most importantly, the structure of corned powder allowed the burning to progress mainly between, rather than within powder grains, resulting in a much more rapid evolution of the solid into gas. (13) Some contemporary master gunners claimed that engrained powder was three times as powerful as the sifted form. (13) This posed a problem, however: the commensurate increase of the pressure in the chamber of the gun was more likely to burst the cannon than improve its effectiveness. (13) This, it seems reasonable to assume, explains the shift away from the “ideal” proportions in the mixing of gunpowder: engrained powder with less saltpeter would be both cheaper and more powerful than sifted powder with the “perfect” proportions, but not so much more powerful that it would be likely to burst the gun. (13)


Reacting to the early superiority of English firearms, the French focused on bettering the design of theirs. (8) They focused on knocking down fortifications, not to use their new designs on the open battlefield. (8) OR by putting batteries of guns in front of troops, the Bureau brothers innovated. (9) Improvements extended to frames and wheels – the carriages – to support and move the cast barrels. (8) The carriages came to be supported by large, stout wagon-type wheels reinforced with iron banding along the rims. (8) The wooden carriages had an extension that angled down behind the wheels and barrel end to make the trail, which could be hitched to another set of wheels and to a team of horses, (8) making them more mobile. (9) The trail also provided the third ‘leg’ with the wheels to make a tripod to hold the barrel when in use. (8) No more hoisting a gun from a wagon bed to a bulky wooden tray on the ground. (8)

Rise of the Bureau Brothers

Jean was appointed “governor of the French archers” and Gaspard was appointed “master of ordinance.” (11) In 1439 Charles VII made Jean Master Gunner of the French artillery. (2,11) Bureau first showed an aptitude for siege warfare during the capture of the English strongholds at in 1437, in 1439, and Pontoise in 1441. (12)In 1437, they helped besiege Montereau, (3,11) OR Montreau (12) and they were also at Meaux OR Meux (12) in 1439, (3,7) OR 1438, where Jean distinguished himself. (7) In recognition Charles VII made him Grand Master of the Artillery of France (7,9) by a royal letter dated 29th September, 1439. (7) The brothers were at Saint-Germain-en-Laye in 1440. (3,11) and they helped suppress the Praguerie rebellion against Charles in 1440. (11) They fought at Pontoise (11,12) OR Pontaise (3) in 1441. (11,12) When Charles VII established a separate branch of service for the artillery as part of his sweeping military reforms of the 1440s, he entrusted Bureau and his brother, Gaspard, to supervise the royal artillery. (12) The brothers gave it clearly defined command, personnel, and administration with uninterrupted procurement and supply. (8) In 1443 Jean became the receiver of Taxes in Paris, and Treasurer General of France. (7) Bishop Bazin, whom Bureau certainly knew, describes him as a man of humble origin, not very tall, but of great determination and courage. (9) According to him, Bureau was (9) a methodical perfectionist, with a mathematical mind; (9,11) a brilliant administrator, (9) and endowed with a lively imagination. (9,11) who knew how to get the best out of his primitive weapons. (11) He was Royal Commissioner of Finances at the Estates of Limousin between 1447 and 1451, (7) and of Marche between 1450 and 1451. (7) He was Provost of the Merchants in Paris from August 1450 to August 1452. (7) Gaspard became artillery clerk, and then temporary master of the artillery by royal letters in 1442. (9) On 27th December 1444 Gaspard (5,9) succeeded Pierre Bessonneau (5) as grand-master of the king’s artillery. (5,9) On 21st March 1445 Gaspard bought the (5) lordship of Villemomble (5,6) from Francis I, Duke of Brittany for 9,000 livres tournois. (5) The brothers were ennobled by royal letters patent in October 1447, (5,7) at Bourges. (7) King Charles VII had the Bureau brothers develop (1,3) an organized and centralized department to procure, distribute and deploy the French artillery in an efficient and effective manner. (3) By the late 1440s the Franco-Burgundian artillery could destroy even the most powerfully defended places. (13) This gave the French army a decisive advantage over the English and helped bring an end to the Hundred Years’ War. (5) In 1448 Jean was made mayor of La Rochelle. (11)


As a prerequisite to the campaigns to retake Normandy and Gascony, the brothers established a number of arsenals and magazines that would support the planned offensives. (12) They quickly updated and enlarged the number of siege and field guns in the king’s army. (12) Where Charles VII had previously had to borrow guns from towns which owned them, he now had enough of his own to attack several places at once, which impressed contemporaries. (9) When the Treaty of Tours (which had established a truce between England and France) ended in 1449, (11) Charles VII launched a campaign to retake Normandy in northern France (8,11) with four armies, all supported with the improved artillery. (8) Bureau acquired a reputation as an effective artillery officer during this campaign. (11) The brothers took part in the conquest of Normandy, (2,3) personally directing the artillery in all the battles there and in Gascony. (7) Jean Chartier, in his Chronique de Charles VII, emphasized the “marvellous … approaches, fosses, entrenchments and mines which the abovesaid [Bureau brothers] had made before all the towns and castles which were besieged” during the reconquest of Normandy in 1450. (13) Bombardments by the Bureaus’ artillery aided in the capture of (11) Rouen (3,11) Harfleur in December 1449, Honfleur in January 1450, and Fresnoy in January 1450. (11) By January 1450, the French had forced the English back to the coast of Normandy. (12)


Determined to keep a foothold in Normandy, the desperate English fought on. (8,12) They mustered sufficient arms (8) and a force led by Sir Thomas Kyriell arrived in Cherbourg under orders (12) to relieve the beleaguered region (11,12) by reinforcing Caen, the second-largest city in Lancastrian Normandy. (12) To counter this force, the Count of Clermont (12) OR the Duke of Bourbon (11) led a French army, (11,12) which included a number of culverins under Bureau’s direction, (12) to contest the English advance. (11,12) The two sides met in open battle at Formigny (8,11) on 15th April (11,12) 1450. (8,11) Bureau aided in the French victory at Formigny (11,12) The French initially attempted to charge the English position, but were driven back by English longbowmen. (11) Although the French normally reserved their artillery for sieges, they made an exception (8) with two pieces (8,11) (likely breechloading culverins), which the Bureaus (11) OR Jean (12) advanced to positions on each of the French flanks opposite the English longbows (11,12) to barrage the English archers (8,11) deployed as they had been at Agincourt. (8) To the consternation of the English, the enemy guns had greater range than the longbows, and the French shelled the longbows with impunity. (11,12) The French failed to provide protection for the cannons, (11) and the English were able to charge and capture them, but were then set upon by French cavalry (8,11) sweeping down on two flanks in the traditional way. (8) The English lost 3,000 – (8) and the battle. (8,11)

Siege Warfare

The English still controlled Caen, Bayeux, Falaise, and the entire Cotentin peninsula, but after Formigny it was only a matter of using the French artillery to reduce England’s last few fortresses in the region. (12) They took advantage of the offensive firepower their siege guns had over the outdated fortifications of the period. (12) Virtually all of the towns and castles still had high walls designed for protection against infantry assault rather than artillery bombardment. (12) French bombards easily battered the walls down (12) Whereas it had taken the English four months to besiege Harfleur, in 1440, eight months to besiege Rouen, in 1418, 10 months to seize Cherbourg, in 1418; by contrast, in 1450, (9) by reducing enemy fortresses in a matter of days or weeks instead of months or years, the Bureaus enabled (12) the Normandy offensive to proceed at a surprisingly rapid pace. (9,12) Charles VII took the whole province, requiring sixty sieges, in a year and six days. (9) Fort after fort fell, garrison after garrison surrendered. (8) A contemporary English document lists one hundred strongpoints (13) OR about 60 sieges, both large and small successfully ended (12) in 1450 (12,13) by the French royal artillery under Bureau’s direction played a crucial role. (12,13) These included Chateau Gaillard, St. Saveur-le-Vicomte, Cherbourg, Roche-Guyon, and Rouen, all of which had earlier required long sieges to capture. (13) The moral influence exerted by the heavy artillery became so great that cities surrendered as soon as it appeared. (9,12) The mere appearance of the dreaded French bombards outside Bayeux was enough to force the English garrison to surrender on May 16, 1450. (12) OR After a sixteen-day siege in 1450, almost the entire wall of Bayeux was “pierced and brought down.” (13) Harfleur, which had held out for four months in 1440, made terms after a seventeen-day bombardment in 1449. (13) The following month, the French besieged Caen. (12) For almost three weeks, Bureau’s artillery train, which included 17 enormous bombards, pounded the city’s walls. (12) Inside those walls, Edmund, Duke of Somerset, commanded a garrison that refused to surrender. (12) When a cannonball crashed through the nursery where Somerset’s children and wife were located, the duke finally called a halt to the resistance and surrendered. (12) Perhaps Bureau’s finest hour occurred during the subsequent (12) siege of Cherbourg. (11,12) Thomas Gower commanded an English garrison there that numbered about 1,000 men. (12) They faced a French army that may have numbered 20,000. (12) In surveying the city from its outskirts, Bureau wished aloud that he could fire on the town from the sea as well as the land, (12) which would ensure a continuous bombardment. (11,12) Not willing to dismiss the idea as impractical, he devised a way to place a number of his guns on the beach. (12,13) To do so, he instructed his gunners to cover the guns in tallow and hides to protect them from salt water during high tide. (12) the Bureaus placed their guns below the high water mark on the town’s seaward side, leaving them submerged during high tide, and returning to resume the bombardment during low tide. (11) The technique worked like a charm, and French gunners were able to shell the city from that position when the tide went back out to sea. (12) “The town received such a heavy battering from cannons and bombards that the like had never been seen before,” wrote an anonymous French chronicler. (12) Cherbourg’s surrender on August 12th marked the end of nearly three decades of English rule in Normandy. (12)


After Normandy had been conquered John was sent as a diplomat and ambassador to Armagnac and Aragon. (7) He was a Commissioner at the trial of Jacques Coeur 1451-3. (7) After the French regained Normandy, they turned to the English holdings in the southwest, ruled by the English crown since the 12th century. (8) In 1451, all of Guienne fell rapidly to the French (8,13) with their artillery, (8) despite the deeply ingrained pro-English sympathies of the inhabitants of the duchy. (13) The French artillery, led by the brothers Jean and Gaspard Bureau, played an important role. (10,11) They were instrumental in the recapture of several cities, including Bordeaux, which surrendered in June. (11) It took only five days at Blaye in 1451 before, “the town walls were completely thrown down in many places. (13) The story was much the same at Dax and Acx: “their walls were so battered in many places that by diverse breaches they could be taken by assault. (13) Leseur and Chartier on the siege of Dax is worth quoting at length: “The watch ordered and set, our prince sent for a force of pioneers and miners, who, all night long, he had make broad approaches and deep ditches and trenches, [and] set up his large artillery, and put the protective mantles there; and he was so diligent that the said artillery was ready to fire at dawn. (13) And in the same way my lord the prince made huts by filling wickerwork and faggots with earth, in the manner of a broad mound, to shelter the watch from the artillery of the town; and the trenches were so advanced the next day that one could go safely under cover from one quarter of the siege to another, and in the same way one could come by the said approaches to the artillery, and even up to their fosses. (13) And always, day and night, the said pioneers worked on them …. (13) Furthermore, the large artillery was fired assiduously day and night. (13) Inside of a few days it had done great damage, so that the defences of the towers … (13) and a great part of the forward walls were thrown down to the ground; and our said artillery made large and wide breaches there, over which watch was held; and we fired the large culverines at these, so that, when the enemy wished to make shelters or otherwise repair them, our culverines often killed and wounded their men and knocked them down to the ground, them and their shelters. (13) Once the campaign of 1451 had succeeded in taking Guyenne, Charles VII appointed Jean perpetual (7) mayor of Bordeaux in 1455. (7) OR in August 1451. (11) He built the Trumpet Tower there. (7) But he got along badly with the Bordelais, in particular the Captal de Buch. (7) The city rose (7,11) and was re-taken by the English in 1452. (7) They turned their artillery against Gascony again (3,7) where they captured Bordeaux and defended Castillon in 1452. (3) Their cannon were used at Bergerac, and against the castles of Montguyon and Blaye. Jean Bureau besieged and took Libourne. (7,9)


On 17th July (9) 1453 (2,9) Jean led the French army in what is considered the last battle of the Hundred Years War, (2) the Battle of Castillon, (2,5) at which he defeated the Earl of Shrewsbury, Sir John Talbot. (2) Knowing Castillon and its surroundings well, having taken it in 1451 with little difficulty, the brothers Bureau seem to have wanted to attract Talbot’s army to a location of which they knew the strategic advantages. (9) Their tactics were successful. (9) They defended the French camp by a ditch in which the artillery was positioned, hidden from the sight of the English. (10) The idea of constructing an artillery park to protect the men and guns from counterattack was not a new one to the French. (12) They had used the concept for about a decade, notably at Dax in 1442, Mauleon in 1449, and Guissen in 1449. (12) At that battle, and the others in Guyenne, the brothers commanded an artillery of 300 different guns, which they had brought to the battlefield down the river Dordogne from the foundries of Périgord. (9). John Talbot, (10,12) the famous English military commander, then about 60 years old, (10) attacked the French camp (10,12) in an impulsive assault (12) with an army of 6,000 men, (10) but no artillery. (12) They were decimated by the firepower of the French artillery. (10) Talbot himself was killed during the confrontation and the English army was destroyed in Guyenne. (10) It was the first time that artillery had had a decisive influence on the outcome of a battle in the West. (9) Pushing out the English gave the French artillery excellent combat experience and the opportunity to determine where refinements were needed. (8) After the battle, the main strongholds of Guyenne fell into the hands of the French. (10) Bordeaux opened its gates in October 1453. (10) When the Hundred Years’ War ended in 1453 (3) Charles VII became the ‘Victorious King’. (10) The Bureau brothers were renowned in France for their skill in artillery management and administration. (3)

Later Life

Later Jean was made Lord of Montglat, (2,7) OR Montglas. (11) La Houssaye-en-Brie (1450), Fontenay-en-France, Thieux and Noisy-le-Sec, Marle and Malmaison (7) and afterwards Mayor of Bordeaux (2,7) in 1455. (7) OR in August 1451. (11) After Louis XI’s solemn entry into the capital he stayed at John’s house ‘Porcherons’. (7) He was knighted (2,7) by Louis XI at his coronation (7) in 1461 (2,7) and made a member of the Royal Council. (7) He and his brother continued to serve as advisors to Charles’ son and successor, Louis XI, even though Louis dismissed most of Charles’ staff. (11) Gaspard became lord of Montfermeil, Nogent-sur-Marne and other places. (6) He was made marquis of Castillon then a knight in 1464. (5) He finally became captain of Beauté, Le Louvre and Poissy between 1463 and 1465. (5) He first married around 1440, to Guarix Burelle, with whom he had no children. (5) His second marriage was around 1450, to Richarde de Vérines, with whom he had three daughters. (5) Jean died (1,2) in Paris on 5th July (2) 1463 (1,2) Gaspard died in 1469. (1,2)


The Bureau brothers’ legacy remained intact over time. (12) They made the French artillery the most effective in the world. (11) The guns next proved their worth in 1494. (8) Their skill and ingenuity in developing, maintaining, and using effectively a large artillery train gave the French kings an upper hand against their foes well into the 16th century. (12) The English were late in this, retaining bows after most of the continent had given them up. (4) As late as 1513 the Battle of Flodden was the last in which longbows were the principal missile weapon. (4) The old laws about all men in England being required to own and practice with longbows fell into abeyance and arquebuses took over. (4) The administration and oversight provided by the Bureau brothers for the French cannons eventually spread to encompass government administration in general, and led to the use of the word ‘bureaucracy’ that so many people love to hate in the modern world. (3) The new iron refining process, and the increasing skills of the gunsmiths, made guns cheaper to buy; and corned powder made them both more powerful and cheaper to use. (13) The number and size of guns in use increased rapidly. (13) Put together, these developments were enough to reverse the centuries-old superiority of the defensive in siege warfare, and bring the walls of medieval castles crashing down. (13) Further important improvements were made in the 1450s to 1470s, including the general adoption of the modern two-wheeled carriage, trunnions, and iron cannonballs. (13) Large bombards increasingly gave way to smaller, cheaper, more easily transportable guns, particularly cast bronze muzzle-loaders. (13) However important these latter changes may have been from a technical point of view, though, it was the earlier changes which held the greatest importance for the actual conduct of operations, as the above analysis of the sieges of the 1410s to 1430s shows. (13)

[bibliography of sources available upon request]

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