[citation needed] On May 17, 1942, Rockwell enlisted in the United States Navy, where he became a group commander of 12 LCT’s during the invasion of Normandy on D-Day, June 6, 1944.

Rockwell received both the US Navy Cross and the French Croix de Guerre avec Paume for his decision to break radio silence when faced with what he recognized as a certain disaster.

Instead, Rockwell radioed an Army captain which allowed important last-minute changes that aided in the success of the attack and saved thousands of lives.

The Navy Cross citation reads, in part: "Rockwell, in the face of very heavy enemy fire, discharged the tanks [he and his men had carried ashore] on the ground.

[2] Author and historian Stephen Ambrose wrote of Rockwell in his book, D-Day, June 6, 1944: The Climactic Battle of World War II: "There was one final bombardment from the sea.