Complex sentence: Born in San Francisco, he attended Lehigh University as member of the class 1941 but with the start of World War II left in his junior year to join the USAAF as an aviation cadet.
Split into simpler sentences: Born in San Francisco, he attended Lehigh University as member of the class 1941. With the start of World War II he left in his junior year to join the USAAF as an aviation cadet.