Lothian expressed relief and said that Chamberlain had done "a marvellous job.... [he is] the only man who steadfastly refused to accept the view that Hitler and the Nazis were incorrigible and would understand nothing but the big stick". The German-born American historian Abraham Ascher wrote that anyone reading of the relationship between Lord Lothian together with the Canadian prime minister William Lyon Mackenzie King "cannot avoid being taken aback by the superficiality and gullibility of these two authors" as both Lord Lothian and Mackenzie King convinced themselves that Hitler was an idealistic man of peace. In late 1938, Lothian read Mein Kampf, which led him to become disillusioned with Nazi Germany. At least part of the disillusionment was because in Mein Kampf, Hitler made it clear that his principal issue was not with the Treaty of Versailles, but rather with the Dolchstoß ("stab-in-the-back") that was alleged to have caused the German defeat in 1918. The implications of these views was Hitler was not angry with the alleged unjust Treaty of Versailles, but rather with the fact that Germany had lost the First World War, as he made it clear that only a German victory in 1918 would have satisficed him. Lothian was prepared to see the Treaty of Versailles revised in favor of Germany, but was he not willing to accept a German-dominated Europe, which he learned from Mein Kampf was what Hitler was seeking. However, he later changed his mind after Hitler's violation of the Munich Agreement by the occupation of Czechoslovakia in March 1939. "Up until then it was possible", he wrote to a friend, Thomas William Lamont, on 29 March 1939, "to believe that Germany was only concerned with recovery of what might be called the normal rights of a great power, but it now seems clear that Hitler is in effect a fanatical gangster who will stop at nothing to beat down all possibility of resistance anywhere to his will". In a speech in the House of Lords in April 1939, Lothian spoke in favor of peacetime conscription, a first in British history as the only way to deter Germany from war. Ambassador to the United States In September 1939, Lothian was appointed Ambassador to the United States, a post he held until his death, the following year. He was sworn of the Privy Council in August 1939 and made a Knight of the Thistle