On March 20, 1862, Roane was appointed to the grade of brigadier-general in the Confederate States Army. After most Confederate troops were moved from Arkansas across the Mississippi River, he was placed in charge of the defense of Arkansas. At this time Arkansas was nearly defenseless; and Roane, with the newly appointed commander of the Trans-Mississippi District (also known as Department Number Two), Major-General Thomas Hindman, cobbled together a reasonable defensive force. Roane took part in numerous battles within the Trans-Mississippi Theater, including the battles of Whitney's Lane and Prairie Grove.