From http://www.rafmuseum.org.uk/milestones-of-flight/british_military/1943_3.html:

The first attack of the Battle of Hamburg on 24-25 July also saw the first use of Window (tinfoil strips dropped from aircraft to simulate aircraft echoes and confuse ground search and nightfighter radars) by RAF Bomber Command. The forerunner of modern ‘chaff’, Window proved very successful – only 12 of the 700 bombers despatched were lost.

I am listening to Electric Universe on CD and it had a piece about chaff. Chaff is interesting because it is a deceptive countermeasure to a defensive technique (radar). Sort of the opposite of a honeypot, if you can follow my harebrained logic.