portfolio. In practice, these five were augmented by the service chiefs and ministers who attended the majority of meetings. The cabinet changed in size and membership as the war progressed, one of the key appointments being the leading trades unionist Ernest Bevin as Minister of Labour and National Service. In response to previous criticisms that there had been no clear single minister in charge of the prosecution of the war, Churchill created and assumed the additional position of Minister of Defence, making him the most powerful wartime Prime Minister in British history. He drafted outside experts into government to fulfil vital functions, especially on the Home Front. These included personal friends like Lord Beaverbrook and Frederick Lindemann, who became the government's scientific advisor. Resolve to fight on At the end of May, with the British Expeditionary Force in retreat to Dunkirk and the Fall of France seemingly imminent, Halifax proposed that the government should explore the possibility of a negotiated peace settlement using the still-neutral Mussolini as an intermediary. There were several high-level meetings from 26 to 28 May, including two with the French premier Paul Reynaud. Churchill's resolve was to fight on, even if France capitulated, but his position remained precarious until Chamberlain resolved to support him. Churchill had the full support of the two Labour members but knew he could not survive as Prime Minister if both Chamberlain and Halifax were against him. In the end, by gaining the support of his outer cabinet, Churchill outmanoeuvred Halifax and won Chamberlain over. Churchill believed that the only option was to fight on and his use of rhetoric hardened public opinion against a peaceful resolution and prepared the British people for a long war – Jenkins says Churchill's speeches were "an inspiration for the nation, and a catharsis for Churchill himself". Churchill succeeded as an orator despite being handicapped from childhood with a speech impediment. He had a lateral lisp and was unable to pronounce the letter s, verbalising it with a slur. He worked hard on his pronunciation by repeating phrases designed to cure his problem with the sibilant "s". He was ultimately successful and was eventually able to say: "My impediment is no hindrance". In time, he turned the impediment into an asset and could use it to great effect, as when he called Hitler a "Nar-zee" (rhymes with "khazi"; emphasis on the "z"), rather than a Nazi