what are they used for?
Long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against powerful short range attackers
Destroyer
In naval terminology, a destroyer is a fast, maneuverable, long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against powerful short range attackers. 
how far is richmond va from newport news va UNANSWERABLE why is the second city named as such? The source of the name "Newport News" is not known can you name some industries that sustain the city economically? Shipbuilding, military, and aerospace can you name some agencies that are involved in the first industry you just mentioned? Newport News Shipbuilding,  CSX Transportation what is the former most well-known for? Designer, builder and refueler of United States Navy aircraft carriers and one of two providers of U.S. Navy submarines did they contribute to the military efforts during the first world war? Yes, it delivered 25 destroyers during the war
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Destroyer [SEP] Introduction
In naval terminology, a destroyer is a fast, maneuverable, long-endurance warship intended to escort larger vessels in a fleet, convoy or battle group and defend them against powerful short range attackers. They were originally developed in the late 19th century by Fernando Villaamil for the Spanish Navy as a defense against torpedo boats, and by the time of the Russo-Japanese War in 1904, these "torpedo boat destroyers" (TBDs) were "large, swift, and powerfully armed torpedo boats designed to destroy other torpedo boats". Although the term "destroyer" had been used interchangeably with "TBD" and "torpedo boat destroyer" by navies since 1892, the term "torpedo boat destroyer" had been generally shortened to simply "destroyer" by nearly all navies by the First World War.