I'm sorry it has taken so long to get back to you.

I've looked at the photo again, and it still looks like the HQ flag for the Armmy of the Potomac Cav Corcs. I think the lines of the superimposed red "C" can be seen crossing one of the sabers in two places.

I have "Civil War Battle Flags of the Union Army and Order of Battle" which reprints "Flags of the Army of the United States Carried During the War of the Rebellion, 1861 - 1865." It pictures Sheridan's personal battle flag as red over white with a white star on the red and a red star on the white and no crossed sabers. It also gives the general pattern of the A of P Cav Corps HQ flag.

I don't know if Sheridan continued to use the HQ flag after he was assigned to command the Army of the Shendoah or if he used it when he returned to the A of P. It may have been used by Torbert and Merritt while they commanded the Cav Corps of the Army of the Shenandoah.

According to "Flags ...." the Cav Corps of the A of P used another flag. This was a swallow tailed, red, white, and blue tricolor divided into three triangles, with yellow or gold crossed sabers on the white triangle.

Ray