Trivial this may be but while researching for the 'What Happened Today' thread I came across something I hadn't realised before..
In December 1944 Bomber Command launched a series of 'Main Force' attacks on the Urft Dam in the Eifel. It's interesting to compare the relative effort : -
617 Squadron sent 19 aircraft on the Dams Raid in May 1943, losing 8 but destroying two dams.
In total, 5 & 8 Group despatched
544 sorties (!

) to the Urft Dam, achieving only 13ft of masonry dislodged from the top of the dam but losing only 2 aircraft.
A 'blunt instrument' indeed....