A major battle fought between British and German forces in northern France during World War I. The battle was planned by Joffre and Haig. Before it began the Germans attacked Verdun, the defence of which nearly destroyed the French army. To relieve pressure on Verdun the brunt of the Somme offensive fell on the British. On 1 July the British advanced from their trenches almost shoulder to shoulder, presenting a perfect target for German machine gunners. The Germans fell back on the Hindenburg Line defences (a barrier of concrete pillboxes armed with machine guns; see Siegfried Line), while for the loss of some 600,000 men the Allies had gained a few kilometres of mud.