4-inch/50-caliber gun
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The 4″/50-caliber gun was the standard low-angle, quick-firing gun for the United States, first appearing on the monitor Arkansas and then used on "Flush Deck" destroyers through World War I and the 1
The gun from USS Ward which fired the first American shot of World War II at Pearl Harbor on 7 December 1941 at the State Capitol grounds in St. Paul, Minnesota.
4-inch/50-caliber gun on merchant ship SS Sommelsdijk
Caldwell-class destroyer
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The Caldwell class was a class of six "flush deck" United States Navy destroyers built during World War I and shortly after. Four served as convoy escorts in the Atlantic; the other two were completed
USS Caldwell (DD-69) in harbor in 1919