9. Sailors in the US Coast Guard were busy throughout the 1920s
During World War I, the Coast Guard was temporarily transferred to the Navy Department. After the war, the service returned to the Department of the Treasury, its then peacetime home. The Volstead Act, which provided the enforcement authority for Prohibition, assigned that role to Treasury (which was why Eliot Ness and the Untouchables were called T-Men). Sailors in the US Coast Guard spent the 1920s hard at work, often at sea and on the Great Lakes, chasing and capturing smugglers of alcoholic beverages. When the 1920s began the Coast Guard consisted of about 4,000 officers and men. During the decade the service grew to over 10,000. It was the only branch of the US armed forces to expand during the 1920s. It acquired new ships, coastal cutters and mothballed Navy destroyers, to aid in the accomplishment of its mission.
In 1925, the Coast Guard acquired its first airplanes, having convinced the Treasury Department that aerial searches greatly enhanced their ability to intercept smugglers. While the other services, particularly the US Army, lost capabilities during the 1920s, primarily because of steadily shrinking budgets, the Coast Guard became a highly effective, well-trained interdiction force. It even gained combat experience in running gun battles with some smugglers. When smugglers adopted coded radio transmissions to communicate, the Coast Guard countered with an increasingly sophisticated signals intelligence group, adept at cracking complex codes. Repeal of Prohibition brought a drawdown for the service, including the loss of the destroyers, but during the 1920s life in the Coast Guard was a busy, dangerous, and exciting career. By 1930 it was arguably the best trained of all the American armed forces.