The Pact of Brunnen (Bund von Brunnen) is a historical treaty between the cantons of Uri, Schwyz, Unterwalden, concluded in Brunnen on 9 December 1315. Representatives of the four territories (Unterwalden was composed of Obwalden and Nidwalden) met in Brunnen after the success of the Battle of Morgarten in the previous month to renew the promise of mutual military assistance. In 1318, Leopold I, Duke of Austria concluded a truce with the confederates.According to Aegidius Tschudi, the pact of Brunnen marks the decision to make what had been a pragmatic alliance a permanent, sworn confederacy, initiating the phase of growth of the Old Swiss Confederacy, with the accession to the pact by Lucerne in 1332 and Zürich in 1351, Glarus and Zug in 1352 and Bern in 1353.