B-17 Flying Fortresses of the 390th Bomb Group, US Eighth Air Force, accompanied by escort fighter aircraft, leave vapour trails in the sky, 23 November 1943. Handwritten caption on reverse: 'Single most famous aerial combat photo. B-17F Plane 'F'. 27 Sept 1943. Raid against Emden, 17th Combat mission of 390BG.' US Official Caption: “TRAILS IN THE SUB-STRATOSPHERE . . . Giving them the appearance of monsters from Mars, the vapor trails left by these Flying Fortresses of the U.S. Army 8th AF leave their marks in the sub-stratosphere. The curved trails, leading upward, were made by the fighters accompanying the B-17's on the raid. The deadly 50 calibre machine guns bristling from the leading Fortress, are plainly visible against the light reflected from the contrails.“