Looks as if I provided the wrong URL for Day's 12th Battalion. It should have been:
During its career the battalion formed part of Rucker's Legion. The writer of this article was understandably reluctant to describe actions in which the battalion was not specifically named. Having studied Vaughn's Cavalry command, I can agree about specific mentions from the Official Records being difficult to find.
We do know that substantial elements of this brigade were dismounted and sent into the Shenandoah Valley to assist in the expulsion of General Hunter's army in June 1864. From Lynchburg, Vaughn's men marched north with Early's army, crossed the Potomac, defeated a Federal force at Monacacy, MD, July 8, 1864, and reached the outer defenses of Washington on July 13th. The Tennesseans were remounted after Early returned to Virginia, and participated in numerous skirmishes and battles. This part of Vaughn's command left Virginia shortly after Early's defeat at Fisher's Hill, Sept. 22, 1864.
Let me know if you have other questions.