Perhaps on 1 August 1291, the cantons of Schwyz, Uri and Unterwalden entered into an Eternal Alliance that would eventually become the Swiss Confederation. The Federal Charter of 1291 was probably prompted by the death of Rudolf I of Habsburg on 15 July 1291 and created a defensive alliance. The "Rütlischwur" (Oath of the Rütli) was another alliance between the Forest Cantons in or around 1308 and brought the cantons closer together. The canton of Schwyz took the leadership in the confederation early on. As early as 1320 the name of the canton was applied to the whole of the confederation. It was only in 1803, however, that the name "Schweiz" as derived from the canton of "Schwyz" became the official name of Switzerland. The flag of Switzerland is derived from the banner of Schwyz.