[citation needed] While receiving flight training, Wehner's German ancestry led to an investigation followed by an unsubstantiated arrest for suspicion of treason by the Secret Service.

Flying as wing man to the mercurial balloon-buster Frank Luke, Wehner shot down one Fokker D.VII and five balloons in just three days of aerial combat during September 1918.

[1] Protecting Luke as he attacked a third balloon, Wehner's SPAD XIII was shot down by Luftstreitkräfte ace Georg von Hantelmann of Jasta 15 on 18 September 1918.

He immediately attacked, destroying one and forcing another down out of control, his own plane being badly damaged by enemy machine-gun fire.

Amid terrific antiaircraft and ground machine-gun fire First Lieutenant Wehner descended, attacked, and destroyed two enemy balloons.