This was covered extensively in my trial and in Richard Evans's report, available on line or in Lying About Hitler. I also discuss it in History on Trial.
Irving responded to Kamm's column with a virulent attack hypothesizing that Kamm's piece was, as Kamm explains in his blog
"commissioned by the newspaper after pressure had been exerted upon it by an external body whose identity (or at least ethnicity) you will be able to guess immediately."People like Irving, i.e. Holocaust deniers, like to inflate the number of dead in Dresden as a means of engaging in "immoral equivalencies," i.e. arguing that while "some" Jews may have "died" [not murdered] in Auschwitz, this number pales by comparison to the number of "innocent" Germans killed in the bombing of Dresden.
Vonnegut helped perpetuate that myth and spread this form of denial. He probably did so initially unwittingly. But since the publication of that book enough has been written to show this is not true and he could have corrected it has he been so inclined.
And so it goes.... on and on and on.