In World War Two the science of antiaircraft gunnery rested on a single, shaky postulate, known as 'the ack-ack assumption': namely, that a raider would fly at constant speed, constant height and on a constant course. Only if this rule was obeyed could the gunners arrange for their salvos to rendezvous with the target, which would travel three or four miles during the half-minute or so it took the rounds to reach the required height. A lone raider could 'jink' to baffle the predictors, though a massed formation of bombers was most unlikely to do so.

LRB 4 July 1985 | PDF Download