Battle of Sempach The Battle of Sempach was fought on 9 July 1386 , between Leopold III , Duke of Austria and the Old Swiss Confederacy . The battle was a decisive Swiss victory in which Duke Leopold and numerous Austrian nobles died . The victory helped turn the loosely allied Swiss Confederation into a more unified nation and is seen as a turning point in the growth of Switzerland . Background . During 1383 - 1384 , the expansion of the Old Swiss Confederacy collided with Austrian interests . The interests of Austria were further undermined in the Pact of Constance , a union of Zürich , Zug , Solothurn and 51 cities of Swabia . In 1385 , there were various attacks , without formal declaration of war or central organization , by forces of Zürich , Zug and Lucern on the Austrian strongholds of Rapperswil , Rothenburg Cham and Wolhusen . In January 1386 , Lucerne expanded its sphere of influence by entering pacts with number of towns and valleys under Austrian control , including Entlebuch , Sempach , Meienberg , Reichensee and Willisau . This move was the immediate cause of war . A local Austrian force defeated the confederate garrison at Meienberg . On 14 January , Lucerne called the confederaces for assistance . An armistice was called on 21 February , and negotiations were held in Zürich . But neither side had any real interest in ending the conflict at this point , and as the armistice ended , the conflict escalated into a full - scale military confrontation . Duke Leopold gathered his troops at Brugg , consisting of his feudal vassals from Swabia , the Alsace , Aargau , Thurgau , Tyrol , as well as bourgeois forces of various towns and Italian , French and German mercenaries . In the course of a few weeks , no less than 167 noblemen , both secular and of the church , declared war on the Swiss . These declarations were sent to the Swiss diet in 20 packets , in order to increase the effect of shock . On 24 June , a messenger from Württemberg brought 15 declarations of war . Before all letters had read , the messenger from Pfirt delivered another eight , and before he had finished speaking , letters from the lords of Schaffhausen were brought in . Another eight messengers arrived on the following day . The gathering of Austrian forces at Brugg suggested an intended attack on Zürich , and the Confederate forces moved to protect that city . But Leopold marched south , to Zofingen and on to Willisau , apparently with the intention of ravaging the Lucerne countryside and perhaps ultimately aiming for the city of Lucerne . The Austrian army had a troop of mowers with them with the purpose of cutting down the corn and destroying the harvests along their route . The town of Willisau was plundered and burned , and the army moved on to Sursee on Lake Sempach , and thence towards Sempach on 9 July . Leopold ' s men taunted those behind the walls of the town , and a knight waved a noose at them and promised them he would use it on their leaders . Another mockingly pointed to the soldiers setting fire to the ripe fields of grain , and asked them to send a breakfast to the reapers . From behind the walls , there was a shouted retort : " Lucerne and the allies will bring them breakfast ! " Confederate troops of Lucerne , Uri , Schwyz and Unterwalden had marched back from Zürich once it became clear that this was not Leopold ' s target . The forces of Zürich had remained behind defending their own city , while those of Bern had not heeded the confederate call for assistance . The Battle . The Confederation army had presumably assembled at the bridge over the Reuss River at Gisikon . It marched from there , hoping to catch Leopold still at Sempach where he could be pressed against the lake . Around noon , the two armies made contact about 2 km outside of Sempach . This was to the mutual surprise of both armies , which were both on the move and not in battle order . But both sides were willing to engage and formed ranks . The site of the battle is marked by the old battle chapel , which was originally consecrated in the year after the battle . The Swiss held the wooded high ground close to the village of Hildisrieden . Since the terrain was not deemed suitable for a cavalry attack , Leopold ' s knights dismounted , and because they did not have time to prepare for the engagement , they were forced to cut off the tips of their poulaine s which would have hindered their movement on foot . The Swiss chroniclers report how a huge pile of these shoe - tips was found in a heap after the battle , and they are also depicted in the background of the battle scene in the Lucerne Chronicle of 1513 . The main body of the Confederation army finally completed its deployment from the marching column , formed up , and attacked the knights from the flank aggressively . The Austrian force , on the other hand , formed a wide rank and threatened to surround the outnumbered confederates . How and at what point the battle turned in favour of the confederates is a matter of debate . It has been suggested that an important factor was the midday heat in July , which wore out the Austrian knights wearing heavy armour much more than the lightly armed confederates ( some of which had reportedly no other " armour " than a wooden plank tied to their left arm as a shield ) . Another factor may have been a fatal underestimation of the confederates on the part of the nobility . According to the account by Tschudi , seeing the small strength of the confederate force , the nobles were concerned that if they sent the mercenaries in front , as would have been common practice , they might not see any action at all , as the mercenaries would finish the job on their own . Therefore they insisted to stand in front , placing the mercenary force behind them . Traditional Swiss historiography since the 16th century has attributed the turning of the tide to the heroic deed of Arnold von Winkelried , who opened a breach in the Habsburg lines by throwing himself into their pikes , taking them down with his body so that the confederates could attack through the opening . Winkelried is usually explained as a legendary figure introduced to explain the Swiss victory against the odds , perhaps as late as a full century after the battle . The earliest evidence of the Winkelried legend is the depiction of the battle in the Lucerne Chronicle of 1513 . The oldest accounts of the battle are unambiguous in the judgement that the Swiss victory was against all odds and expectations , and is attributed to the grace of God . In any case , the Swiss did break through the Austrian ranks and routed the enemy army completely . Duke Leopold and with him a large number of nobles and knights were slain , including several members of the noble families of Aarberg , Baldegg , Bechburg , Büttikon , Eptingen , Falkenstein , Hallwil , Reinach , Rotberg and Wetter . Aftermath . An armistice was agreed upon on 12 October , followed by a peace agreement valid for one year , beginning on 14 January 1387 . The battle was a severe blow to Austrian interests in the region , and allowed for the further growth of the Old Swiss Confederacy . Already weakened by the 1379 division of Habsburg lands , Leopoldian control of the territories left of the Rhine would collapse over the following years , not least due to the death toll among the local elites loyal to Habsburg . This allowed the confederate cities , especially Lucerne , Bern and Solothurn , an unchecked expansion into the undefended Habsburg lands . Bern , which had not participated in the Sempach war , took the opportunity and began its conquest of what would become the canton of Bern , sending military expeditions into the Jura , the Oberland , Emmental and Aargau . Lucerne by 1389 was able to consolidate its control over the towns around lake Sempach , Willisau and the Entlebuch , largely corresponding to the extent of the modern canton of Lucerne . Glarus also took the opportunity to rebel against Habsburg control and established its independence in the Battle of Näfels in 1388 . A new peace agreement between the confederacy and Austria was concluded on 1 April 1389 , valid for seven years , extended to 20 years on 16 July 1394 . Legacy . Not without justification , the Battle of Sempach came to be seen as the decisive turning point between the foundation of the confederacy as a loose pact in the 14th century , and its growth into a significant political and military power during the 15th century . At the peak of the military success of the Eight Cantons in the period of 1470 to 1510 , Swiss historiography paid great attention to the Battle of Sempach . It is depicted in the Swiss illustrated chronicles of the period , and discussed by Reformation era historiographers such as Aegidius Tschudi and Wernher Steiner . Since there are few historiographical accounts of the battle predating 1470 , it is difficult to judge the historicity of the individual details . The legend of Arnold Winkelried is recorded in this period , but it cannot be shown to predate 1500 . The battle chapel at Sempach was consecrated already in 1387 . A yearly mass was celebrated there on the day of the battle . The chapel was repeatedly enlarged . It was decorated with a fresco in 1551 , which was restored and enlarged in 1638 – 1643 , 1695 , 1741 – 43 , 1747 , and 1886 . The current fresco is largely a restoration of the painting of 1643 . Swiss patriotism in the restored Confederacy of 1815 – 1847 rediscovered the formative phase of the Old Confederacy as a source of national identity . The modern " Sempacherlied " is a product of 1830s patriotism . During the World Wars , the Swiss policy of armed neutrality was also ideologically fuelled by reference to the military successes of the medieval confederacy . Swiss modernist author Robert Walser ( 1878 – 1956 ) recounts the Battle of Sempach in brief but violent detail in his short story " The Battle of Sempach " .