After a week-long artillery bombardment, the offensive began at 07.30 on 1 July 1916.  Unconvinced that the inexperienced soldiers of Kitchener’s New Armies could cope with more sophisticated tactics, some senior commanders ordered the infantry to advance in long, close-formed lines although some adopted more flexible attack formations.

In most places the artillery bombardment had failed to cut the German barbed wire or harm the defenders in their deep dugouts. German machine-gunners emerged from shelter and mowed down the oncoming British infantry.  The only substantial British success was in the south where, using more imaginative tactics and helped by the French artillery on their immediate right, the 18th and 30th Divisions took all their objectives, including Montauban, and the 7th Division captured Mametz.  At Thiepval the 36th (Ulster) Division seized the Schwaben Redoubt but was forced to withdraw because of lack of progress on its flanks.

These limited gains cost 57,470 British casualties, but there was no question of suspending the offensive with the French still heavily engaged at Verdun.  Haig no longer expected an immediate breakthrough; he now regarded the Somme as an attritional or 'wearing-out' battle.