Born on 19 April 1892, He began school in Bayreuth in 1912, studying mechanical engineering. After several attempts to volunteer for service at the beginning of World War I, he was accepted by the pioneers at
Ingolstadt. He trained in Darmstadt in 1916; one of his schoolmates from high school,
Richard Wenzl, trained with him there and would also become an ace. Weiss began his aerial service as an observer gunner in artillery cooperation units FA(A) 282, FA(A) 28, and FA(A) 68 during June 1916. At that time, he was a corporal. During a reconnaissance flight, he was wounded in the foot by anti-aircraft fire while flying at nearly 9,000 feet. Upon recovery, he was awarded the Iron Cross Second Class. On a later mission, on 26 May 1917, he bombed an enemy supply train, breaking it in half; he then continued the attack despite ground fire from machine guns and infantry. He won the Iron Cross First Class and was promoted to sergeant for this feat. ==Service as a fighter pilot==