In May 1940, as a trusted friend, Wood told Chamberlain "affectionately but firmly" that after the debacle of the British defeat in Norway and the ensuing Commons debate, his position as Prime Minister was impossible and he must resign. He also advised Winston Churchill to ignore pressure from those who wanted Lord Halifax, not Churchill, as Chamberlain's successor. Chamberlain agreed to resign on 9 May, but considered going back on his decision the next day as the German attack on the Western Front had begun; Wood told him that he had to go through with his resignation. Both men acted on Wood's advice. Churchill became Prime Minister on 10 May 1940; Wood was appointed Chancellor of the Exchequer on 12 May.