With the attack on Poland on September 1, 1939, National Socialist Germany triggered World War II. Determined by its declaration of guarantee to the Polish state, Great Britain and Northern Ireland declared war on Germany on September 3, 1939. Hitler, who had not expected British intervention until the end, was surprised by the declaration of war. A major result of the Chamberlain’s persistent peace policy was the unity with which the British nation and the Commonwealth of Nations entered the war.
According to Neovideogames, N. Chamberlain initially remained head of government and formed a war cabinet to which Churchill and Eden now also belonged. After the early German successes in 1940 in the western theater of war, which were favored by the defensive French and British warfare, the governing majority in the lower house shrank, so that A. N. Chamberlain was forced to resign on May 10, 1940. Churchill now formed a coalition cabinet in which, in addition to the Conservatives, v. a. Labor Party politicians were also represented; their leader in the House of Commons, C. Attlee, became Deputy Prime Minister. Under the pressure of the war, the domestic political disputes faded into the background. With the recognition of the British trade union federation TUC as an equal political partner of the government, the internal cohesion of the country was to be promoted. Union leader E. Bevin was appointed to the government. Strikes and lockouts were banned, wages and working conditions improved. With the Beveridge Plan (1942/43; William Baron Beveridge of Tuggal) and the Education Act (1944), social reforms were initiated. The British economy was placed in the service of arms production, but despite their own efforts Great Britain and Northern Ireland were crucially dependent on aid supplies from the USA (Lend Lease System, 1941). To secure the essential supply of goods (including food), the government acquired large parts of the Norwegian and Greek merchant fleet. About half of the war expenditure was covered by the state on credit (the external debt grew to £ 3.5 billion).
Great Britain and Northern Ireland were initially unsuccessful in the theater of war. A planned landing operation in Norway was preceded by the German occupation of Denmark and Norway in April 1940. The British expeditionary force in France had to withdraw to Great Britain and Northern Ireland at the end of May / beginning of June 1940 – pushed back by the German troops to the Dunkirk area. When Churchill, after the French collapse (June 1940), found no response to his proposal for an “Anglo-French Union” and France concluded an armistice with Germany and Italy, he supported General C. de Gaulle’s Founded Comité National Français (CNF; German-French National Committee). On July 4, 1940, the French government under Marshal P. Pétain broke off diplomatic relations with Great Britain and Northern Ireland after the French fleet had been bombed by British units off Oran. Great Britain and Northern Ireland now stood up to Hitler’s Attack on the Soviet Union only against National Socialist Germany, nevertheless rejected all peace initiatives and by thus maintaining the front in the West it created an important prerequisite for the later defeat of Germany. In August 1940, the German air war against Great Britain and Northern Ireland began, which led to severe destruction in English cities (including London, Coventry), but the British Air Force was able to prevent German success. The deployment of British troops in Greece in 1941 was unsuccessful, and threatening setbacks occurred in North Africa until the summer of 1942. In the East Asian theater of war, Great Britain and Northern Ireland suffered heavy losses against Japan: Hong Kong surrendered on December 25, 1941 and Singapore on February 15, 1942.
Together with the American President F. D. Roosevelt, Churchill proclaimed the principles of a future peace order in the Atlantic Charter (August 14, 1941). After the German attack on the USSR (June 1941) and the USA entered the war (December 1941) Great Britain and Northern Ireland, the USSR and the USA united to form the “anti-Hitler coalition”, the v. a. formulated common war goals at the conferences in Tehran (1943) and Yalta (February 1945, Yalta conference). At the Casablanca Conference (1943) Churchill and Roosevelt called for it the “unconditional surrender” of Germany and Italy. With the landing of their forces in Normandy (June 1944) Great Britain and Northern Ireland and the USA established a second front against Germany; they began a major attack that led their armed forces to Germany under heavy fighting until May 1945.
As after the First World War, Great Britain and Northern Ireland came out of the battle victorious in 1945, but nevertheless decisively weakened. As a great power, it was henceforth in the shadow of the USA and the USSR, which had decided the war. Not only were there high losses, the country’s economic and social policy also faced difficult tasks. There were profound changes in the British Empire and the Commonwealth; In terms of foreign policy, the descent from a world power to a European power was on the way.