There were also battles west of the Mississippi River Valley in the Trans-Mississippi Theater. For example, two important battles were the Battle of Wilson's Creek and the Battle of Pea Ridge. The Confederates tried to invade New Mexico in February and March 1862 but they were defeated at the Battle of Glorieta Pass. After the Union captured Vicksburg, the area became separated from the rest of the Confederate States. Other battles happened in the area after the capture of Vicksburg.