This type of film concentrates on the U.S. cavalry and the lives of the soldiers within it. A subgenre of both the western and the military-life drama in many cases, it often deals with the pressures of living the cavalry lifestyle and the havoc it wreaks on the family life of soldiers. The films are inevitably highlighted and/or capped off by a spectacular fight against warring Indian tribes as they attack either a settlement protected by the cavalry or the cavalry base itself. The quintessential films are John Ford's trilogy of life in the U.S. cavalry: (Fort Apache, She Wore A Yellow Ribbon, and Rio Grande) which examined their role in the westward expansion of the United States. Using the cavalry forts as a microcosm of society, it also examines issues of authority and patriarchy in the military, as well as commenting on the replacement of the "Wild West" by law and order.