The Revenue Cutter Service, the federal bureau that enforced treaties and tariffs on the seas and inland waterways, established its officer training school at Fort Trumbull in 1910. Fort Trumbull offered easy access to Long Island Sound, which was a good place to practice drills, however, the Revenue Cutter Service found the buildings uncomfortable and bleak. Rear Admiral Earl G. Rose called the post "tall in weeds, a stony and forlorn-looking place, devoid of creature comforts."
Congress merged the Revenue Cutter Service and the Life Saving Service in 1915 to form the U.S. Coast Guard, and the school became the Coast Guard Academy. Two years later, with the entry of the United States into World War I, hundreds of Coast Guard seaman recruits flocked to Fort Trumbull for training. The twelve cadets enrolled at the academy at that time helped prepare the new recruits for service. Several temporary wooden buildings were hastily constructed for living and teaching space. Many of the recruits trained at Fort Trumbull served on cutters that escorted ships between Gibraltar and Britain.
In 1920 the Eighteenth Amendment went into effect and made the sale and consumption of alcohol illegal - ushering in the turbulent period known as Prohibition. Widespread illegal activity resulted in the need for more Coast Guard personnel to prevent smuggling along the coast. Section Base Four, a Coast Guard division responsible for patrolling the New London area, came to Fort Trumbull in this period. The Day, New London's newspaper, described "sensational action," in 1932 when the Coast Guard seized a rum-running speedboat after a seventy-mile chase.
The academy moved to its present location up the Thames River in 1932, but the Coast Guard continued to operate a radio school, a pharmacy school, and other training programs at Fort Trumbull into the early 1940s. A Coast Guard station responsible for search and rescue and law enforcement on Long Island Sound remains on the waterfront here today.