Federal Charter of 1291

The Federal Charter or Letter of Alliance (German: Bundesbrief) is one of the earliest constitutional documents of Switzerland. A treaty of alliance from 1291 between the cantons of Uri, Schwyz and Unterwalden, the Charter is one of a series of alliances from which the Old Swiss Confederacy emerged. In the 19th and 20th century, after the establishment of the Swiss federal state, the Charter became the central founding document of Switzerland in the popular imagination.

The Charter documents the Eternal Alliance of the League of the Three Forest Cantons (German: Ewiger Bund der Drei Waldstätten), the union of three cantons in what is now central Switzerland. It is dated to early August 1291, which in the 20th century inspired the date of Swiss National Day, 1 August. Done in Latin, the Charter makes reference to a previous (lost or unwritten) pact. It is now exhibited at the Museum of the Swiss Charters of Confederation in Schwyz.