In Aug 1864 when Sheridan reached the Shenandoah' Duffie's and Averell's cavalry divisions were occupied elsewhere. Sheridan had only a small brigade commanded by Col C. R. Lowell. Lowell's brigade consisted of his own 2nd Mass Cav, a regiment of MD cavalry from what was called the Potomac Home Brigade, and the 25th NY Cav. Later and for a brief time this brigade was assigned to Merritt's 1st Division.
However Bvt Brig Gen Devin, commanding the 2nd Brigade of the 1st Division, was wounded in mid Aug and was absent for nearly a month. In early Sep 64 Merritt's division was reorganized. Col Gibbs' who was previously in command of the Reserve Brigade was transferred with his regiment to Devin's brigade, and Gibbs took command of that unit until Devin's return. Lowell's brigade was disbanded. The MD regiment was dismounted, the 25th NY Cav was transferred to Custer's brigade, and Lowell and his regiment were sent to the Reserve Brigade. Lowell then assumed command of Reserve brigade until he died of wounds received at Cedar Creek. The Reserve brigade's 6th Pa Cav (Rush's Lancers) was sent to the Pleasant Valley remount depot to muster out and reorganize as a 6 company battalion.
There was some confusion at the recent LBHA Conference regarding which brigade Loweel was commanding when Mosby's men were executed in late Sep 1864. This is the group of excecutions Custer has been blamed for. Lowell, however, stated that it was the division commander who gave the order.