In May 1913, Ehrlich joined the army and served with the infantry until his transfer to the French Air Service in December 1916. He received a Pilot's Brevet in May 1917 and was assigned to N154. Cited for actions against the enemy on 10 August 1917, he was badly wounded while strafing the German lines. Promoted to Sergent, he returned to duty in November 1917. On the evening of 18 September 1918, three days after he was recommended for the Légion d'Honneur, Ehrlich was shot down and captured after scoring his 19th victory. The following day, his promotion to Sous Lieutenant was announced. In all, Ehrlich destroyed 18 balloons and shot down an Albatros scout in less than three months.
"Remarkable pursuit pilot who has distinguished himself by his exceptional audacity and tenacity which have earned him twelve victories in one month. He flamed three balloons in a few minutes. One wound. Three citations." Médaille Militaire citation, 10 September 1918