Has there ever been a strategic bomber raid completely wiped out? Question in title. All them seem to be heavily damaged but with half surviving at least. Cant find any that were wiped out.
If you mean a "heavy bomber flight" being one that was completely destroyed, then yes... And it happens to be a very famous one...

The Dolittle Raid consisted of 16 bombers that bombed Tokyo on April 18, 1942. All but 1 of the original 16 aircraft crashed in China, with one landing in Russia. 


Source: Wikimedia