make it three times as powerful as before. These changes led to the increased power in the artillery weapons of the time. Joan of Arc encountered gunpowder weaponry several times. When she led the French against the English at the Battle of Tourelles, in 1430, she faced heavy gunpowder fortifications, and yet her troops prevailed in that battle. In addition, she led assaults against the English-held towns of Jargeau, Meung, and Beaugency, all with the support of large artillery units. When she led the assault on Paris, Joan faced stiff artillery fire, especially from the suburb of St. Denis, which ultimately led to her defeat in this battle. In April 1430, she went to battle against the Burgundians, whose support was purchased by the English. At this time, the Burgundians had the strongest and largest gunpowder arsenal among the European powers, and yet the French, under Joan of Arc's leadership, were able to beat back the Burgundians and defend themselves. As a result, most of the battles of the Hundred Years' War that Joan of Arc participated in were fought with gunpowder artillery. The army of Mehmet the Conqueror, which conquered Constantinople in 1453, included both artillery and foot soldiers armed with gunpowder weapons. The Ottomans brought to the siege sixty-nine guns in fifteen separate batteries and trained them at the walls of the city. The barrage of Ottoman cannon fire lasted forty days, and they are estimated to have fired 19,320 times. Artillery also played a decisive role in the Battle of St. Jakob an der Birs of 1444. Early cannon were not always reliable; King James II of Scotland was killed by the accidental explosion of one of his own cannon, imported from Flanders, at the siege of Roxburgh Castle in 1460. The able use of artillery supported to a large measure the expansion and defense of the Portuguese Empire, as it was a necessary tool that allowed the Portuguese to face overwhelming odds both on land and sea from Morocco to Asia. In great sieges and in sea battles, the Portuguese demonstrated a level of proficiency in the use of artillery after the beginning of the 16th century unequalled by contemporary European neighbours, in part due to the experience gained in intense fighting in Morocco, which served as a proving ground for artillery and its pratical application, and made Portugal a forerunner in gunnery for decades. During