Can't think why I hadn't mentioned it before, but one of the simplest, most devilishly-effective weapons to catch the enemy by surprise has to be 'Schrage Musik', the upward-slanting MG-FF cannon used by the Nachtjagd.

Designed 'in the field', this mounting of what were effectively obsolete weapons was absolutely devasting, and it took the RAF an incredible amount of time to 'cotton on', preferring instead to believe in 'scarecrow shells', etc....

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"Stand by to pull me out of the seat if I get hit" - Guy Gibson