Battle of Morgarten
1315 CE.
Shown on the map at 47.090°, 8.633°.
The Battle of Morgarten took place on 15 November 1315, when troops of Schwyz, supported by their allies of Uri and Unterwalden, ambushed an Austrian army under the command of Leopold I, Duke of Austria on the shores of Lake Ägeri, in the territory of Schwyz. After a brief close-quarters battle, the Austrian army was routed, with numerous slain or drowned. The Swiss victory consolidated the League of the Three Forest Cantons, which formed the core of the Old Swiss Confederacy.
Text from the Wikipedia article Battle of Morgarten, licensed CC BY-SA 4.0.