At the start of World War I strategy was dominated by the offensive thinking that had been in vogue since 1870, despite the more recent experiences of the Second Boer War (1899–1902) and Russo-Japanese War (1904–05), where the machine gun demonstrated its defensive capabilities. By the end of 1914, the Western Front was a stalemate and all ability to maneuver strategically was lost. The combatants resorted to a "strategy of attrition". The German battle at Verdun, the British on the Somme and at Passchendaele were among the first wide-scale battles intended to wear down the enemy. Attrition was time-consuming so the duration of World War I battles often stretched to weeks and months. The problem with attrition was that the use of fortified defenses in depth generally required a ratio of ten attackers to one defender, or a level of artillery support which was simply not feasible until late 1917, for any reasonable chance of victory. The ability of the defender to move troops using interior lines prevented the possibility of fully exploiting any breakthrough with the level of technology then attainable.