Bombing of Dresden is the jewel in the crown of that doctrine.
It is important to say that FDR in 1939 urged warring parties to refrain from bombing civillians and Britain had this policy until May 15 1940.
Something else. Rotterdam and Coventry bombing are generally taken as the halmark of Nazi savagery.
However, the USAAF and RAF bombing of Belgrade on Easter Week of 1944 (april 16,17,21,24), murdered two times more civilians than Nazis in Rotterdam (2000 vs. 900) and four times more than Nazis murdered in Coventry. Germans had 18 casualties. Communications were not hit, only civilian targets. The inscriptions "Happy Easter" found on UXO shows that bobming of civilians was planned and deliberate.
It was Lindemann's doctrine at work, with small distinction - Belgrade was the capital of an allied country under German occupation, not Hitler's ally.
Oops, typo. It should read: When Churchill became PM May 10, 1940,"
Do you speak German?