When the United States entered World War I in 1917, naval aviation was in its infancy with only 43 qualified pilots (five of them Marines) supported by 239 enlisted men. The Navy owned only 54 planes, most of which were not fit for wartime service. But when the war ended 19 months later in November 1918, nearly 7,000 naval officers wore the gold wings and green uniforms associated with naval aviation. The number of enlisted men in aviation units had grown to more than 30,000, and there were now over 2,000 planes.
Navy airplanes, blimps, and special balloons that could be launched and towed from ships carried out a variety of missions during the relatively short period of American participation in the war. Naval aviation personnel operated from 27 different bases in France, England, Ireland, and Italy, flying bombing missions against submarine pens along the coast of Belgium and raiding airfields, supply dumps, canals, and railroads. They performed reconnaissance missions, patrolled submarine-infested waters, and provided convoy protection. They were credited with sinking at least one U-boat and damaging a number of others. After the war, Secretary of the Navy Josephus Daniels reported that during the last ten months of the war, no convoy guarded by airplanes or blimps suffered a single ship lost.
One mission near the end of the war was particularly noteworthy. On 21 August 1918, a flight of U.S. Navy aircraft led by Ensign George H. Ludlow flew from their Italian base on the Adriatic to drop propaganda leaflets on the Austro-Hungarian submarine base at Pola. The three fighters in the group were Macchi M.5 flying boats that had been introduced less than a year earlier. By modern standards, they were quite odd-looking aircraft but were very fast and maneuverable for the time and armed with two potent Vickers guns.
As they approached their target, a flight of seven enemy Phönix land fighters rose to meet them, and a spirited dogfight ensued. Ensign Ludlow shot down one of the Austrians, but his own aircraft was hit several times and burst into flames. He managed to put out the fire by throwing the aircraft into a tight spin, but his engine went dead and he spiraled downward toward the Adriatic. A skilled pilot, Ludlow managed to land on the water within sight of the enemy submarine base. No longer flying, the "boat" now began to sink as well, and Ludlow might well have perished or been captured were it not for his wingman, Ensign Charles H. Hammann. Although his aircraft was not designed to carry more than one person, and despite the danger posed by the enemy fighters still buzzing about like angry hornets, Hammann landed near Ludlow's sinking plane and, while firing on the crippled aircraft to accelerate its sinking and keep it from falling into enemy hands, waited for Ludlow to swim over. With Ludlow clinging precariously to the Macchi's struts, Hammann coaxed his plane into the air, made a final strafing pass on the downed fighter, and headed back to base. The imbalance caused by Ludlow forced Hammann to crash land, but he managed to do it without causing serious injury to either man.
For his gallantry, Charles Hammann was awarded the Medal of Honor—the first won by a U.S. Navy flyer.