1916–1918: the end of the war

In 1916 Germany attacked the French fortress of Verdun on the Western Front (from 21 February); the fighting lasted until December, about 700,000 men from both sides were killed, wounded or missing, and the front hardly changed. To relieve Verdun, French and British forces attacked on the Somme on 1 July; the battle lasted until 18 November, ended with enormous losses and an advance of only a few kilometres. At the Somme Britain used tanks for the first time, in September. On the Eastern Front in June 1916 (from 4 June; 22 May old style) General Brusilov led the Russian armies in Galicia and broke through Austro-Hungarian defences; this badly weakened Austria-Hungary, though Russia itself suffered heavy losses. Romania joined the Entente on 27 August 1916, but most of it was occupied by the end of the year. From 1 February 1917 Germany declared unrestricted submarine warfare; this, together with the sinking of neutral ships (the sinking of the Lusitania in 1915 had already angered American opinion), led the USA to declare war on Germany on 6 April. The USA was already tied to the Entente by loans and supplies; its troops began to arrive in France in the summer of 1917 and shifted the balance in the Entente’s favour.