Through the spring of 1912, a series of bilateral agreements between the Christian Balkan states (Greece, Bulgaria, Montenegro and Serbia) formed the Balkan League, which in October 1912 declared war on the Ottoman Empire. In the First Balkan War, the Ottomans were defeated on all fronts, and the four allies rushed to grab as much territory as they could. The Greeks occupied Thessaloniki just ahead of the Bulgarians, and also took much of Epirus with Ioannina, as well as Crete and the Aegean Islands.