Complex sentence: He was a private in World War I before becoming an actor, and determined to become a popular radio and television actor, his career began on stage where he got his first role in a silent film called "The Silent Witness" (1917).
Split into simpler sentences: He was a private in World War I before becoming an actor. Determined to become a popular radio and television actor, his career began on stage where he got his first role in a silent film called "The Silent Witness" (1917).