When the United States entered the First World War in April 1917, the most pressing tactical problem on the Atlantic was the German submarine campaign. Convoys of cargo ships were being hunted to the bottom on the approaches to Britain and Ireland; Allied shipping losses had reached a level the war could not sustain for much longer. The American response included a network of small naval air stations on the Irish coast, sited to put aircraft and observation balloons over the convoy routes where the U-boats were thickest. Five sites were chosen for U.S. Navy operations: Berehaven on Bantry Bay, Lough Foyle in the north, Queenstown - now Cobh - on Cork Harbour, Wexford on the southeast coast, and Whiddy Island in Bantry Bay itself. Berehaven would be the only one dedicated to kite balloons.

Ensign Carl E. Shumway of the United States Naval Reserve Force took command on 26 April 1918. The station was formally commissioned three days later, on 29 April. The location had been chosen because the natural shelter of Berehaven - the long sound between the Beara mainland and Bere Island, the second-safest natural harbour in the world - made it possible to handle large fragile balloons in conditions that would have torn them apart elsewhere. The destroyers that would actually deploy the balloons in combat, however, were based forty miles up the coast at Queenstown, and that geographical mismatch would haunt the operation. Balloons cannot easily be flown across open water from one base to another. They have to be either transferred on the deck of a slow-moving ship or, in practice, launched fresh from where the destroyer would actually rendezvous.

The base did what it could. Practice flights were made from trucks towed across the open ground around the station, the balloons running on long tethers as the trucks moved - approximating, on land, what a balloon-towing destroyer at sea would feel like. Balloons were flown at around five hundred feet, where an observer in clear conditions could see a U-boat's periscope wake from perhaps eight or ten miles away. In late July and early August 1918, the operations were extended to support balloon flights from American battleships - three battleships had been sent to Europe to help shield the Allied convoys approaching Ireland, and they operated out of Bantry Bay. Berehaven supplied the balloons. Through late August and October the work continued, with the station carrying sixteen balloons at peak strength.

By the latter part of October 1918, the Navy had decided to relocate the lighter-than-air work to Queenstown to make the balloons easier to get to the destroyers. Then the Armistice of 11 November ended the war before the move could be completed. The anti-submarine patrols stopped. The remaining aircraft and balloons were grounded and disarmed. Berehaven was the only U.S. Navy kite balloon station in the British Isles. Its final inventory at the Armistice was sixteen balloons, an officer corps of reserve ensigns and lieutenants who had been mostly civilians a year and a half earlier, and the working knowledge of how to run a hydrogen plant on a rainy Cork hillside. The base was formally disestablished on 12 February 1919.

Berehaven itself remained a Royal Navy base through the interwar period - it was one of the three Treaty Ports retained by Britain after Irish independence, not finally handed back until 1938. The American kite balloon installation has left almost no physical trace on the ground around Castletownbere. What remains is a footnote in the much longer story of this harbour and a reminder that for nine months in the closing year of the First World War, sailors from New England and the Midwest stood on a Cork hillside watching the sky and waiting for orders that, in the event, came in the form of a peace they had not expected. The hydrogen plant is gone. The mooring lines are gone. The balloons were packed away in 1919 and there is no record of where they ended up.