Caesar made an ill-planned and disorganised landing in Africa on 28 December 47. He had insufficient food and fodder, which forced him to break up his forces to forage. Piso's light cavalry effectively disrupted these efforts, notably at the Battle of Ruspina when he harassed Caesar's defeated army as it retreated to its camp. The two armies continued to engage in small-scale skirmishes while Caesar waited for reinforcements. Then two of the "optimates"' legions switched to Caesar's side. Emboldened, Caesar marched on Thapsus and besieged the city at the beginning of February 46. The "optimates" could not risk the loss of this position and were forced to accept battle. Scipio commanded "without skill or success", and Caesar won a crushing victory which ended the war.