Lewis Hancock, Jr. was born 15 October 1889 at Austin, Texas. He entered the Naval Academy in 1906.

After graduating with the Class of 1910, he entered the submarine service. He was awarded the Navy Cross for his exploits and commanding officer of L-4 during World War I.

Lieutenant Commander Hancock died 3 September 1925 near Caldwell, Ohio, in the crash of lighter-than-air ship Shenandoah.