Bob is correct that 6644 is the D-Day heritage unit, but it is not army green. It is WW2 RCAF spitfire aircraft camouflage with D-Day identification Stripes.
Per the original CPR announcement on the Military units
“CP 6644 wears the camouflage colours applied to Royal Canadian Air Force "Spitfire" fighter planes flown at the Allied invasion of Normandy, France, on June 6, 1944.”
https://www.cpr.ca/en/media/canadian-pacific-honours-canadian-us-military-with-special-locomotives
Regards,
Stephen Gardiner
Toronto, ON
