I found this cover and I almost fell off my chair when I realized who this man was after a morning of research. The cover was sent from Limbourg, Belgium on December 23, 1944 during the Battle of the Bulge by Col Severne S MacLaughlin Hqrs of 3rd Armored Group.
Prior to Operation Neptune on June 6, 1944, Tank units equipped with DD tanks were trained at Torcross, England by Colonel MacLaughlin, the US 3rd Armored Group commander. To keep secret the nature of this training, the area was sufficiently far removed from Slapton Sands to avoid observation by the remainder of the troops.
The DD tank training consisted of teaching tank crews to launch their tanks and using the duplex drive to drive them ashore under their own power on the surface of the water. Once ashore they abandoned their buoyancy equipment and proceeded as normal tanks. The Duplex Drive (DD) tank was designed to be used at the D-Day landings. The Duplex Drive tank was meant to give the Allies mechanised armour on the beaches of Normandy – a weapon that would surprise the Germans defending the beaches there, who would have expected only troops in a beach landing as opposed to tanks. The Duplex Drive tank met with success at Juno Beach but failed to give the Americans the cover they needed at Omaha Beach..
Ten tank battalions were distributed among British, Canadian, and American forces for the D-Day assault on Normandy. On Sword, and Utah Beaches, the majority of the DD tanks successfully swam to shore. On Gold Beach the tanks were brought directly to the shore by landing craft due to high seas. On Juno Beach, only some of the tanks were launched because of high seas. But on Omaha Beach, 27 of the 29 DD tanks sank at sea in six foot waves, after being launched three miles from the beach.
I have provided a link for more information about Armor in Operation Neptune below. Note that the Colonel's name has been spelled differently than how he spelled it on the cover-