Bulgarian-German Treaty of 1915, on Friendship and Alliance

signed in Sofia on August 24 (September 6). Bulgaria pledged to enter World War I on the side of Germany, which guaranteed Bulgaria’s territorial integrity and also, according to an additional secret agreement, its territorial acquisitions at the expense of neighbor states. In addition to the Bulgarian-German Treaty of 1915, a military convention between Germany, Austria-Hungary, and Bulgaria was signed on the same day in Plessa.