There were about 3,500 Union defenders present during the Battle of Lexington.
3rd Illinois Volunteer Infantry Regiment, "The Irish Brigade" - Colonel James A. Mulligan
14th Missouri Home Guard Regiment - Lt. Colonel Robert White
Lafayette Home Guard Battalion - Major F.W. Becker
13th Missouri Volunteer Infantry - Colonel Everett Peabody
1st Illinois Volunteer Cavalry - Colonel T.A. Marshall
U.S. Reserve Corps Infantry Battalion - Major R.T. Van Horn
27th Missouri Mounted Infantry - Lt. Colonel B.W. Grover
Volunteer Cavalry Battalion - Major M.P. Berry