Missourians side with the Union by a…
March 1862 CE
Pro-Confederate Governor Claiborne F. Jackson and his small state guard under General Sterling Price had linked up with Confederate forces under General Ben McCulloch.
After victories at the Battle of Wilson's Creek and at Lexington, Missouri, Confederate forces had been driven out of the state by the arrival of large Union forces in February 1862 and are effectively locked out by defeat at the Battle of Pea Ridge, Arkansas, on March 6–8.