Late in the year, Robertson was assigned a field command, leading first a brigade and later a division of cavalry. Robertson participated in a victory over Union troops at the First Battle of Saltville in Smyth County, Virginia on October 2. Many of the Federal troops participating were negroes, and over 100 were massacred by a group of guerillas associated with Robertson's troops on October 3. Robertson had bragged to another officer that "he had killed nearly all the Negroes." His conduct was such that when Robert E. Lee learned of it he communicated to General John C. Breckinridge his dismay "that a general officer should have been guilty of the crime you mention" and instructed Breckinridge to "prefer charges against him and bring him to trial." One of his subordinate officers, Champ Ferguson, was executed by hanging after the war for his part in what the Northern press deemed the "Saltville Massacre." Historian William C. Davis, in his book "An Honorable Defeat. The Last Days of the Confederate Government" (2001), said that Robertson personally "join(ed) in the act of villainy", although he escaped prosecution.