The Battle of St. Jakob an der Birs was fought between the Old Swiss Confederacy and French (mostly Armagnac) mercenaries, on the banks of the river Birs. The battle took place on 26 August 1444 and was part of the Old Zürich War. The site of the battle was near Münchenstein, Switzerland, just over 1 km outside the city walls of Basel, today within Basel's St-Alban district. Background In 1443, the seven cantons of the Old Swiss Confederacy invaded the canton of Zürich and besieged the city. Zürich had allied with Frederick III, Holy Roman Emperor, who now appealed to Charles VII of France to send an army to relieve the siege. Charles, seeking to send away the "écorcheurs", troublesome troops made idle by the truce with Henry VI of England in the Hundred Years' War, sent his son the Dauphin (later Louis XI of France) with an army of about 30,000 of these écorcheurs into Switzerland, most of them Armagnacs, to relieve Zürich. As the French forces entered Swiss territory at Basel, the Swiss commanders stationed at Farnsburg decided to send an advance troop of 1,300, primarily young pikemen. These moved to Liestal on the night of 25 August, where they were joined by a local force of 200. The battle In the early morning, they managed to surprise and rout French vanguard troops at Pratteln and Muttenz. Enthused by this success, and despite strict orders to the contrary, the Swiss troops crossed the Birs to meet the bulk of the French army of some 30,000 men, which was ready for battle. Immediately the Swiss forces formed three pike squares of five hundred men each, and they fought well when Armagnac cavalry charged again and again and were repulsed. Aeneas Silvius Piccolomini (1405–1464, later Pope Pius II, until 1439 participant in the Council of Florence), described the battle in vivid detail, telling how the Swiss ripped bloody crossbow bolts from their bodies and charged the enemy even after they had been pierced by spears or had lost their hands, charging the Armagnacs to avenge their [own] deaths. The fighting lasted for several hours and was of an intensity evoking awed commentary from witnesses. Eventually, the Swiss pike squares weakened, so the commander ordered his men to retreat into a small hospital of St. Jakob. A small reinforcement from Basel was repulsed, and its leader, Henman Sevogel, was killed. The