Complex sentence: In 1941, he became Professor of Neurology and Neurological Surgery at the University of Illinois in Chicago where he spent 13 years, and during World War II was a medical consultant to the U.S. Army.
Split into simpler sentences: In 1941, he became Professor of Neurology and Neurological Surgery at the University of Illinois in Chicago, where he spent 13 years. During World War II he was a medical consultant to the U.S. Army.