To General H. W. Halleck.

Executive Mansion, Washington January 7, 1863.

MAJOR-GENERAL HALLECK.

MY DEAR SIR:—What think you of forming a reserve cavalry corps of, say, 6000 for the Army of the Potomac? Might not such a corps be constituted from the cavalry of Sigel's and Slocum's corps, with scraps we could pick up here and there?

Yours truly,

A. LINCOLN.