Key to Union Commander-in-Chief Ulysses S. Grant’s Virginia offensive was man-to-man marking of his opposite number, the talismanic Robert E. Lee. President Lincoln agreed with Grant that if Lee’s Army of North Virginia could be destroyed, whether in open battle or by attrition, the Confederacy would fall. At North Anna, the heavily outnumbered Lee proved adept at avoiding both. On 23 May, the first round went to the Union, with General Warren’s Fifth Corps fording the river and driving the Confederates back. Overnight, Lee improvised the rapid creation of a line of defence, its apex located at Ox Ford. The following day Wright and Hancock’s commands crossed the river, probing the Confederate flanks; an assault from the east was repulsed in heavy rain. Unbeknownst to Grant, Lee and most of his generals were prostrate from illness or injury. Unwilling to risk splitting his army, Grant withdrew north of the river.