Ernest C. Castle was born in Sioux Falls, South Dakota in 1926. He graduated from the United States Naval Academy in 1948. Castle was awarded the Silver Star for conspicuous gallantry in clearing a fouled mine from the otter of the during operations off Korea in May 1952. He was the Naval Attaché to Israel during both the USS "Liberty" incident and the Six-Day War. Castle served as US Navy investigator for the USS Liberty Incident. Additionally, he served as military briefer for Robert McNamara during the Cuban Missile Crisis. He received the Meritorious Civilian Service Award from US President John F. Kennedy for his work during the crisis.