An "Expeditionary Force" refers to a military unit organized to deploy quickly to a specific area for a particular mission, often involving combat or peacekeeping operations. These forces are typically composed of various branches of the military, including the Army, Navy, and Air Force, and are designed to operate in diverse environments. Historically, expeditionary forces have been used in conflicts such as World War II and the Gulf War. They are characterized by their ability to mobilize rapidly and sustain operations away from their home base, often requiring logistical support and coordination with allied nations.