Complex sentence: In 1943, aged 16, he became a "Luftwaffenhelfer" (Air Force "helper"), then he was conscripted into the "Reichsarbeitsdienst" (National Labor Service).
Split into simpler sentences: In 1943, at age 16, he became a "Luftwaffenhelfer" (Air Force "helper"). Soon thereafter, he was conscripted into the "Reichsarbeitsdienst" (National Labor Service).