Complex sentence: As the Second World War began, he stayed in Paris until 1945 and studied Political Science; he was shortly gaoled for participating in protests against the Nazis, and upon his release returned to Syria to teach at the University of Damascus.
Split into simpler sentences: As the Second World War began, he stayed in Paris until 1945 and studied Political Science. He was imprisoned for a short period during that period for participating in protests against the Nazis, and upon his release returned to Syria to teach at the University of Damascus.