Square D: The only remaining World War II tail marking

  • Published
  • By Tech. Sgt. Kevin Wallace
  • 100th Air Refueling Wing Public Affairs
RAF MILDENHALL, England --  How many Team Mildenhall Airmen know their Square D heritage?

Chances are, an Airman could do an entire two- or three-year tour at RAF Mildenhall, see the Square D emblem on assigned KC-135 Stratotankers and view Square D products on the base website, and never really know its significance.

Tipping his hat to that heritage, Mark Howell, 100th Air Refueling Wing historian, would have none of that, and hopes all Team Mildenhall can learn the base's long and proud history.

"At the beginning of World War II, the US Army Air Force was a small service in comparison to the air forces of Europe," said Howell. At first, the USAAF's deployment to Europe involved relatively small numbers of fighters and bomber aircraft, and no system of group identification was used.

Though there wasn't an official marking system, some aircraft were identified by numbers painted on their fuselage.

The Royal Air Force, a much larger air force than America's at the time, used a two-digit code to denote a squadron and a third single letter to identify the aircraft within the squadron, said Howell. That system was impractical in combat, so by June 1943, the first tail system appeared.

"During World War II, bomb groups departing from England joined massive formations over the North Sea before heading toward their targets on [continental Europe]," said Howell. "In order to ensure members from the same group met and formed together, the bombers had tail marking unique to each bomb group."

According to historic documentation, tail markings consisted of a letter within a geometric shape. In the case of the 100th Bomb Group, the unit the 100th ARW descended from, the marking was the letter "D" inside a square - hence the Square D was formed.

The Square D became the official designation of the 3rd Air Division and the subordinate 100th BG, who moved to RAF Mildenhall during the war.

To this day, the 100th ARW is the only Air Force unit to continue using their World War II tail marking. Though the Army Air Force, 3rd Division, 4th Bombardment Wing and 100th Bomb Group only remain in history books, their legacies live on through the 100th ARW and their Square D tail marking.


Editor's note: According to Howell, the Box D was an aberration of the original designation. Personnel not familiar with the original intent or heritage began to refer to the 'Square D' as the 'Box D.'