In early 1944 the RAF tested the M10 Smoke Tanks on Mustangs, Typhoons, and Tempests during exercises but they were never used operationally. For D-Day, Bostons from 88 and 342 (Free French) Sqn were fitted with chemical tanks and dispensing system in the bomb bay. Each aircraft could lay a curtain approximately 5000 ft long.
Operation Smoke Screen began in the early morning hours of 06 Jun creating a smoke curtain from Le Harve to the Cherbourg Pennisula. 88 Sqn was assigned "Gold", "Juno", and "Sword" landing areas and 342 Sqn "Utah" and "Omaha". From the memoir of an 88 Sqn navigator, they were briefed to take off at 0430 hrs, maintain 500 ft ASL until crossing the coast and then dropping to wave top level. As they entered the east end of the assault area they were to contact HMS Ramillies (he's still waiting for Ramillies' response), fly down the line of bombarding ships at deck level while they were engaging shore targets. As they reached the end of the line, north west of Bayeux, they turned toward the beach head, making their run from west to east. Completing the run, a port turn took them past Le Havre and home in time for tea and medals.
Cheers,
RichB