The Missouri State Guard (MSG) was a state militia organized in the state of Missouri during the early days of the American Civil War. While not initially a formal part of the Confederate States Army, the State Guard fought alongside Confederate troops and, at times, under regular Confederate officers.

The Fourth District/Fourth Division was formed of troops from the counties of Gentry, Harrison, Mercer, Grundy, De Kalb, Daviess, Livingston, Clinton, Caldwell, Ray, Carroll, and Worth, and was led by William Y. Slack.

From the Order of Battle at the Battle of Wilson's Creek:

Division, Brigade, & Regiments and Others

Third Division - BG William Y. Slack

Hughes' Infantry - Col John T. Hughes

Thornton's Infantry - Maj. C. C. Thornton

Rives' Cavalry - Col Benjamin A. Rives