query: When did France get involved in World War I?
passage: French Army in World War I
By 1918, towards the end of the war, the composition and structure of the French army had changed. Forty percent of all French soldiers on the Western Front were operating artillery and 850,000 French troops were infantry in 1918, compared to 1.5 million in 1915. Causes for the drop in infantry include increased machine gun, armored car and tank usage, as well as the increasing significance of the French air force, the Service Aéronautique. At the end of the war on November 11, 1918, the French had called up 8,817,000 men, including 900,000 colonial troops. France suffered over 4.2 million casualties, with 1.3 million dead.
passage: World War I
German strategy for a war on two fronts against France and Russia was to rapidly concentrate the bulk of its army in the West to defeat France within four weeks, then shift forces to the East before Russia could fully mobilise; this was later known as the Schlieffen Plan. On 2 August, Germany demanded free passage through Belgium, an essential element in achieving a quick victory over France. When this was refused, German forces invaded Belgium on 3 August and declared war on France the same day; the Belgian government invoked the 1839 Treaty of London and in compliance with its obligations under this, Britain declared war on Germany on 4 August. On 12 August, Britain and France also declared war on Austria-Hungary; on the 23rd, Japan sided with the Entente, seizing German possessions in China and the Pacific. In November 1914, the Ottoman Empire entered the war on the side of the Alliance, opening fronts in the Caucasus, Mesopotamia and the Sinai Peninsula. The war was fought in and drew upon each powers' colonial empires as well, spreading the conflict to Africa and across the globe. The Entente and its allies would eventually become known as the Allied Powers, while the grouping of Austria-Hungary, Germany and their allies would become known as the Central Powers.