and claimed that Hitler's War was "indispensable to anyone seeking to understand the war in the round". During Irving's lawsuit against Deborah Lipstadt, Keegan — whom he had subpoenaed to appear as a witness — lambasted Irving by saying: "I continue to think it perverse of you to propose that Hitler could not have known until as late as October 1943 what was going on with the Jewish people" and, when asked if it was perverse to say that Hitler did not know about the Final Solution, answered "that it defies common sense". In an article in The Daily Telegraph of 12 April 2000, Keegan spoke of his experience of the trial, writing that Irving had an "all-consuming knowledge of a vast body of material" and exhibited "many of the qualities of the most creative historians", that his skill as an archivist could not be contested, and that he was "certainly never dull". However, according to Keegan, "like many who seek to shock, he may not really believe what he says and probably feels astounded when taken seriously". In the 1990s, Irving featured on his website a translation of a letter by the prominent German historian Hans Mommsen, praising Irving's skill as a researcher. Mommsen, who had written the letter in 1977, unsuccessfully attempted to have it removed, but did succeed in forcing Irving to feature a second letter from him written in 1998 in which Mommsen completely disavowed his 1977 letter under the grounds that he did not wish to be associated with Irving's recent statements about the Holocaust. In a six-page essay in The New York Review of Books published on 19 September 1996 the American historian Gordon A. Craig, a leading scholar of German history at Stanford University, wrote about Irving's claim that the Holocaust never took place and his description of Auschwitz as merely "a labor camp with an unfortunately high death rate". Though "such obtuse and quickly discredited views" may be "offensive to large numbers of people", Craig argued that Irving's work is "the best study we have of the German side of the Second World War" and that "we dare not" disregard his views. Craig called Irving a "useful irritant"; a "devil's advocate" historian who promoted what Craig considered to be a twisted and wrong-headed view of history, with a great deal of élan, but his advocacy of these views forced historians to make