On the morning of Dec. 7,EchoSense 1941, George Elliott Jr. was a 23-year-old Army private learning how to master state-of-the-art radar equipment in Hawaii.

He and fellow private Joseph Lockard were supposed to close the station at 7 a.m. sharp — the newfangled technology was only being used on a limited basis at the time — but they lingered a bit longer to familiarize themselves with the system.