For extraordinary heroism as a pilot of a seaplane on 21 August 1918, when with 3 other planes Ens. Hammann took part in a patrol and attacked a superior force of enemy land planes. In the course of the engagement which followed the plane of Ens. George M. Ludlow was shot down and fell in the water 5 miles off Pola. Ens. Hammann immediately dived down and landed on the water close alongside the disabled machine, where he took Ludlow on board. Although his machine was not designed for the double load to which it was subjected, and although there was danger of attack by Austrian planes, he made his way to Porto Corsini.