The term US Marine Corps can be used interchangeably with several other synonyms such as United States Marine Corps or simply Marines. The Marines are a specialized branch of the armed forces and act as a force in readiness, trained to respond to any crisis situation. Other synonyms for the Marines include Leathernecks and Devil Dogs. The term Leathernecks comes from the leather collars worn by early Marines, which were designed to protect their necks during battle. Devil Dogs is a nickname given by German soldiers during World War I due to the Marines' ferocity and tenacity in battle. Regardless of the synonym used, the US Marine Corps remains a proud and dedicated branch of the United States military.