Two short wars, fought between Serbia, Montenegro, Greece, Romania, Turkey, and Bulgaria for the possession of remaining European territories of the Ottoman empire. In 1912 Greece, Serbia, Bulgaria, and Montenegro formed the Balkan League. In October 1912 the League armies captured all but Constantinople (now Istanbul). European ambassadors intervened to re-draw the Balkans map to the advantage of Bulgaria and detriment of Serbia in the Treaty of London (May 1913). A month later, Bulgaria launched a pre-emptive attack on the Serbs and Greeks, who coveted Bulgaria's gains, but was defeated. In the Treaty of Bucharest (August 1913) Greece and Serbia partitioned Macedonia, and Romania gained part of Bulgaria. Albania, which had been under Turkish suzerainty, was made an independent Muslim principality. A ‘big Serbia’ now presented a considerable threat to Austria‐Hungary. Russia promised to support Serbia in its nationalist struggle and Germany offered military aid to Austria-Hungary. The assassination of the Austrian heir apparent, Archduke Francis Ferdinand, at Sarajevo (1914) gave Austria-Hungary the pretext to invade Serbia, leading to the outbreak of World War I six weeks later.