[4] In April and May 1863, 2,400 Legion soldiers, including 300 cavalrymen, were assigned to help try to stop Grierson's Raid from reaching Baton Rouge.

During the Battle of Plains Store on May 21, 1863, Confederate and Union forces had already fought and disengaged by the time Colonel Miles arrived with reinforcements from Port Hudson.

[6] Nevertheless, late in the day, Miles launched an attack, with some initial success, but was eventually forced to retreat by a counterattack.

[3][10] Victorious General Nathaniel P. Banks paroled the enlisted men, but the officers were made prisoners of war.

[3] The cavalry battalion continued to fight in Mississippi and Louisiana under Major James T. Coleman,[3] before disbanding in the spring of 1865.