The use of the atomic bombs against Japan in the summer of 1945 has been debated endlessly (including here), but I have always thought that it was more significant that, by that stage, the Allies had long since put aside any qualms that they had against using air power against Axis civilians. By one view, the raid was justified given the need to end the war and end the brutal persecution of civilians in occupied countries by the Axis. USAF reports suggest that Dresden had hundreds of armament factories worked by slave labour, producing weapons and munitions for the Third Reich. By that assessment, the bombing of Dresden, along with the bombings of other German cities, bought the war to a faster end and the Holocaust along with it. The alternative view is that Dresden was a cultural and historical landmark of little military significance, and the raid was a disproportionate act of revenge against an already-beaten Germany for the V1 and V2 attacks against Britain and Allied military setbacks in the Netherlands and the Ardennes.
The attack on Dresden was controversial at the time and has remained so. Like a lot of people, I probably gave it the most thought after I read Kurt Vonnegut’s Slaughterhouse-Five. The novel is, pretty transparently, Vonnegut’s attempt to deal with witnessing the destruction of the city first-hand as a prisoner of war. As he later wrote:
The Dresden atrocity, tremendously expensive and meticulously planned, was so meaningless, finally, that only one person on the entire planet got any benefit from it. I am that person. I wrote this book, which earned a lot of money for me and made my reputation, such as it is. One way or another, I got two or three dollars for every person killed. Some business I'm in.