If you had spent more than a few minutes thinking about it, Ansel 'ol Buddy, you'd remember that the Marine Corps is the only service that can be directly deployed by the President for limited expeditionary missions for short periods of time. Beirut, Santo Domingo, the landings at Mogadishu (or Peking or Nicaragua or Port-au-Prince, if you're into history) are just some examples. The Marine Corps is configured specifically to be a pre-packaged, self-sustaining force in increments from a MEU (battalion-sized with air support and combat service support) up to MEF (Division plus air wing plus Service Support Group) with sufficient supplies for 60 days of operations.
Army doesn't do that and doesn't have that charter. They'd like to, but they don't.
Need to read more than comic books Ansel if you want to increase your knowledge of real-world capabilities.