The Swabian War, which was an attempt by the Habsburgs to assert control over the Grisons and key alpine passes, started at the convent.[6] On 20 January 1499, Habsburg troops occupied the surrounding valley and plundered the convent, but were soon driven back by the forces of the Three Leagues at the Battle of Calven. Following the raid, an armistice was signed between the Habsburgs and the Three Leagues. However this armistice only lasted a few days before the conflicts broke out between the Three Leagues' Old Swiss Confederacy allies and the Habsburg troops. These raids quickly escalated into the Swabian War, which ended in September 1499 with the Treaty of Basel granting virtual independence to the Swiss Confederacy.