The following day, Union Generals Crook and Wright arrived at Snicker's Gap and determined to attack what they mistakenly thought was a light picket line of Confederates along the river, left to cover Early's retreat up the Valley. Instead of allowing his cavalry to cross the river and reconnoiter the Confederate positions to confirm this assumption, he dispatched them to Ashby's Gap to attack Early's supply train, which was traveling to the south of Early's main army. Wright then developed a plan where a small Federal force would cross the river northward, downstream from the main crossing at Castleman's Ferry and flank the Confederate position. Gen. Crook assigned Col. Joseph Thoburn to this task.