It is my understanding that Van Dorn lobbied Jeffeerson Davis (a personnal Friend from Mississippi) for the Trans Mississippi post because it carried the rank of Major General and recieved that post by appointment from Jefferson Davis taking command or effective January 11, 1862. (OR's)

However, it was also my impression that he was really wanting a command that covered the State of Mississippi, his and Davis home state, and that is the reason that he so readily abandon his command in the Trans-Mississippi in the face of Curtis' Union Army to go defend Mississippi.