Marshal

Marshal or Field Marshal (known as General of the Marine Corps in the Federation military) is a military rank, the equivalent of which is used by the service organizations of many civilizations. As a traditional grade, marshal is the most senior flag officer rank possible in an organization (a marshal outranks general or admiral). This type of rank is usually reserved for wartime or very large military forces. In comparison to other ranking systems, this rank is somewhat equivalent to the Cardassian Union's quasi-military legate title. During Earth's Second World War, "five star" generals and admirals were created to give America a rank equivilent to European Field Marshals.

From Memory Alpha -- the free Star Trek reference