The Union Army in Missouri included thousands of Missouri State Militia cavalry, which would play a key role in defeating Price, together with the XVI Corps of Maj. Gen. Andrew J. Smith. These were augmented by Maj. Gen. Alfred Pleasonton's cavalry division, detached from William S. Rosecrans's Department of Missouri. As Price commenced his campaign, Smith's corps was on naval transports leaving Cairo, Illinois to join Gen. William T. Sherman's army in Georgia; Rosecrans requested these troops be assigned to Missouri to deal with the threat, and Army Chief of Staff Henry W. Halleck immediately complied. By mid-October, more troops had arrived from the Kansas border under Maj. Gen. Samuel R. Curtis, Price's old adversary at the Battle of Pea Ridge and commander of the newly activated Army of the Border. Curtis commanded the divisions of Maj. Gen. James G. Blunt (cavalry), Maj. Gen. George W. Dietzler (Kansas Militia), Pleasonton's cavalry, and two infantry divisions from Smith's corps under Colonels Joseph J. Woods and David C. Moore—about 35,000 men in all. The Confederates were already greatly outnumbered.