Sheridan and his two cavalry divisions left their camps north of Cold Harbor at 5 a.m. on June 7. They crossed a pontoon bridge at New Castle over the Pamunkey River and headed northwest, with Gregg's division in the lead, Torbert's following. The weather was hot and enormous clouds of dust billowed over the march. On the first day, the column was able to march only about 15 miles. Numerous horses collapsed under the strain, and following the convention Sheridan used in his May raid to Yellow Tavern and Richmond, they were shot and left at the side of the road. Although there were 125 wagons following Sheridan's column, the men were issued only three days' rations and were expected to feed themselves and their horses along the way; dismounted foraging parties spread out along the route. On the second day, with Torbert's division in the lead, the Federals made better progress, covering the 25 miles to Pole Cat Station on the Richmond, Fredericksburg, and Potomac Railroad. The Union column was plagued not only by the heat and humidity of the Virginia summer; skirmishing with irregular mounted raiding parties delayed the advance.