Bulgarian–Ottoman convention (1915)

It quickly became clear that Bulgaria sought a rectification of the border, and Germany and Austria-Hungary put pressure on their Ottoman ally to accept.

The German ambassador to Turkey, Hans von Wangenheim, was unconvinced by the proposed alliance, believing that Romanian neutrality could only be secured by Austro-Hungarian territorial concessions.

On 17 August, the Turkish minister of war, Enver Pasha, wrote to the German chief of staff, Erich von Falkenhayn, to see if an Austro-German offensive against Serbia was forthcoming.

[4] It also left Edirne (Adrianople) vulnerable to Bulgarian attack, but signature of the accord was dependent on a military convention being signed between Bulgaria, Austria-Hungary and Germany.

Bulgaria agreed to allow the transit of German and Austro-Hungarian supplies through its territory to the Ottoman Empire and to invade Serbia with a large force.