Aberdeen Proving Ground (APG) is a United States Army facility located near Aberdeen, Maryland (in Harford County).The Army's oldest active proving ground, it was established on October 20, 1917, six months after the United States entered World War I. The location allowed design and testing of materiel to take place near contemporary industrial and shipping centers. The first gun was fired there on January 2, 1918. APG was created as a successor to the Sandy Hook Proving Ground, which was too small for some of the larger weapons being tested. At the peak of World War II, Aberdeen Proving Ground had billeting space for 2,348 officers and 24,189 enlisted personnel.
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