An armed yacht was a yacht that was armed with weapons and was typically in the service of a navy. Their speed and maneuverability made them useful as patrol vessels. In the United States Navy armed yachts were typically private yachts expropriated for government use in times of war. Armed yachts served as patrol vessels during the Spanish-American War and World War I. In the latter conflict, armed yachts were used as patrol vessels, convoy escorts, and in anti-submarine duties.