Preoccupied with internal problems, France paid little attention to foreign policy in the 1911–14 period, although it did extend military service to three years from two over strong Socialist objections in 1913. The rapidly escalating Balkan crisis of 1914 caught France unaware, and it played only a small role in the coming of World War I. The Serbian crisis triggered a complex set of military alliances between European states, causing most of the continent, including France, to be drawn into war within a few short weeks. Austria-Hungary declared war on Serbia in late July, triggering Russian mobilization. On 1 August both Germany and France ordered mobilization. Germany was much better prepared militarily than any of the other countries involved, including France. The German Empire, as an ally of Austria, declared war on Russia. France was allied with Russia and so was ready to commit to war against the German Empire. On 3 August Germany declared war on France, and sent its armies through neutral Belgium. Britain entered the war on 4 August, and started sending in troops on 7 August. Italy, although tied to Germany, remained neutral and then joined the Allies in 1915.