"The Polish Air Force in the Second World War" What the Spitfire dive-bombers could do. Explosions straddle German flak positions close to the shoreline on Walcheren Island. This attack, carried out by Spitfire XVIs of one of the squadrons of the No 131 (Polish) Wing, was part of a sustained 'softening-up' campaign by No 84 Group and the bomber forces in advance of an amphibious assualt on the fortified island.