Trench warfare
Trench warfare prevailed on the Western Front from late 1914 until the Germans launched their Spring Offensive on 21 March 1918. After the buildup of forces in 1915, the Western Front became a stalemated struggle between equals, to be decided by attrition. Frontal assaults, and their associated casualties, became inevitable because the continuous trench lines had no open flanks. Casualties of the defenders matched those of the attackers, as vast reserves were expended in costly counter-attacks or exposed to the attacker's massed artillery. There were periods in which rigid trench warfare broke down, such as during the Battle of the Somme, but the lines never moved very far. The war would be won by the side that was able to commit the last reserves to the Western Front.
Battle of the Trench
The men from Banu Khuza'a reached Muhammad in four days, warning him of the Confederate armies that were to arrive in a week. Muhammad gathered the Medinans to discuss the best strategy of overcoming the enemy. Meeting the enemy in the open (which led to victory at Badr), and waiting for them inside the city (a lesson learnt from the defeat at Uhud) were both suggested. Ultimately, the outnumbered Muslims opted to engage in a defensive battle by digging deep trenches to act as a barrier along the northern front. The tactic of a defensive trench was introduced by Salman the Persian. Every capable Muslim in Medina including Muhammad contributed to digging the massive trench in six days. The ditch was dug on the northern side only, as the rest of Medina was surrounded by rocky mountains and trees, impenetrable to large armies (especially cavalry). The digging of the ditch coincided with a near-famine in Medina. Women and children were moved to the inner city. The Medinans harvested all their crops early, so the Confederate armies would have to rely on their own food reserves.