The Battle of the Somme (French: Bataille de la Somme, German: Sommeschlacht), also known as the Somme Offensive, took place during the First World War between 1 July and 18 November 1916 on either side of the river Somme in France. The battle saw the British Army, supported by contingents from British imperial territories, including Australia, New Zealand, Newfoundland, Canada, India and South Africa, mount a joint offensive with the French Army against the German Army, which had occupied large areas of France since its invasion of the country in August 1914. The Battle of the Somme was one of the largest battles of the war; by the time fighting paused in late autumn 1916, the forces involved had suffered more than 1 million casualties, making it one of the bloodiest military operations ever recorded.

The plan for the Somme offensive evolved out of Allied strategic discussions at Chantilly, Oise in December 1915. Chaired by General Joseph Joffre, the commander-in-chief of the French Army, Allied representatives agreed on a concerted offensive against the Central Powers in 1916 by the French, British, Italian and Russian armies. The Somme offensive was to be the Anglo-French contribution to this general offensive and was intended to create a rupture in the German line which could then be exploited with a decisive blow. With the German attack on Verdun on the River Meuse in February 1916, the Allies were forced to adapt their plans. The British Army took the lead on the Somme, though the French contribution remained significant.

Somme (French pronunciation: [sɔm]) is a department of France, located in the north of the country and named after the Somme river. It is part of the Picardy region of France.

The north central area of the Somme département was the site of a series of battles through the Great War. Particularly significant was the 1916 Battle of the Somme. As a result of this and other battles fought in the area the department is home to many military cemeteries and several major monuments commemorating the many soldiers from various countries who died on its battlefields.

At the beginning of the First World War, during the September 1914 Race to the Sea, the Somme became the site of the Battle of Albert. The battle was a five day engagement between the 25th and 29 September, with the French Tenth Army attacking at Albert and pushing toward Bapaume, and the German Sixth Army counter-attacking back towards Albert. The line settled around the town of Thiepval and remained there until July 1916, when the Battle of the Somme would be fought on and around the same ground.