Lewis "Lew" Wallace was born on April 10, 1827, in Brookville, Indiana.
He was the second of four sons born to Esther French Wallace (née Test) and David Wallace. Lew's father, a graduate of the U. S. Military Academy in West Point, New York, left the military in 1822 and moved to Brookville, where he established a law practice and entered Indiana politics.
David served in the Indiana General Assembly and later as the state's lieutenant governor, and governor, and as a member of Congress.
Lew Wallace's maternal grandfather was circuit court judge and Congressman John Test.