Churchill ceded British sovereignty on 24th December, 1943 to the USA. Command of Britain’s armed forces became the responsibility of Dwight D. Eisenhower: after this date British generals reported to him. Churchill made his unique decision because Britain was incapable of independent action. Only an American led invasion of Occupied Europe could defeat Nazi Germany. As a result Britain became a junior partner* in the alliance ceasing to be a Great Power. This left two Great Powers: the Soviet Union and the USA.
Churchill had astutely extrapolated the events of 1943 into political policy. American troops in Britain, by late 1943, outnumbered the British. America’s logistical support, provided through the Lend-Lease programme, was evidence of Britain’s client state role. Roosevelt demanded that an American general become Supreme Commander and, notwithstanding Churchill’s special relationship with him, it was a political fait accompli. Churchill couldn’t refuse. A global war meant onlyGreat Powers could compete. In Europe that meant the USA. In the east it meant the Soviet Union.
The Soviet Union fought the land war alone until D-Day,June 1944. The scale of the eastern front dwarfed anything Britain could contemplate. The five month battle of Stalingrad, which ended in February 1943, was stupendous. The combined totals of the combatants was over two million men leading to the annihilation of the German 6th Army. This was followed by the battle of Kursk, which lasted in different phases for six weeks. The Soviets deployed 2.5 million men and 7,360 tanks at Kursk. The contrast with Britain’s victory at El Alamein couldn’t be more stark. That two and half week battle, in 1942, had 1,029 tanks and a 195,000 men on the British side. In Soviet terms El Alamein was a skirmish. In the European land war, the Soviet Union was pre-eminent. Their massive human resources, brilliant generals and willingness to use attrition ground Germany down. Whether the Allies invaded or not, Nazi Germany would be defeated. This offered the possibility of a Soviet empire stretching from Valdivostok to Calais.
Britain was tangentially involved in the Pacific war. The Burma campaign was a side-show, notwithstanding the gallantry of Wingate’s soldiers. Ghandi’s Quit India campaign petered out in early 1943 but was a potent signal that British imperialism was finished. Jailing tens of thousands of his followers stopped the campaign but it remained a political force. Everywhere Churchill looked he saw British decline.
The pre-eminence of the USA was obvious but that of the Soviet Union was more oblique. Ceding sovereignty to the USA wasn’t traumatic. The delusion was that ceding sovereignty was temporary. This was the default position in the 1940s and for generations afterwards. Even so Anthony Eden, Churchill’s Foreign Secretary, bridled at the loss of sovereignty to the USA,** but he didn’t resign.
Churchill knew that Britain’s pretensions were dead and buried by 1943. Begging for material assistance from the USA via Lend Lease acknowledged British sovereignty was under intense strain. The quixotic declaration of war by Hitler in December 1941 brought the USA into a two-front war. Because of their massive economy and manpower they defied Bismarck’s dictum that two-front wars end in defeat. The Soviet Union was severely rocked by Operation Barbarossa, June 1941, but bounced back to deal deadly blows at Stalingrad and Kursk. The appointment of Eisenhower as Supreme Commander was confirmation of Britain’s diminution. Britain relinquished Great Power status to the USA and the Soviet Union in 1943.
* In an astonishing comment on the pervasive delusion of British politicians, ‘John Major has claimed the UK is no longer a “great power” and slammed Brexit as a ‘bitterly divisive policy‘. (my emphasis) This statement was made in 2020 77 years after Churchill ended British pretensions.
** With tragic consequences. He completely misread President Eisenhower in 1956 with the ill-fated incursion into Egypt after the nationalisation of the Suez Canal.
For the Lend Lease programme see https://www.thoughtco.com/the-lend-lease-act-2361029#:~:text=World%20War%20II%3A%20The%20Lend-Lease%20Act%201%20Background.,Pearl%20Harbor%20in%20December%201941.%20More%20items…%20
For the battle of Stalingrad see https://www.bing.com/search?q=battle+of+stalingrad&form=ANNTH1&refig=a6ea57ea2e4843a29e9854791bb5d93f&sp=1&qs=LS&pq=battle+of+sta&sk=PRES1&sc=8-13&cvid=a6ea57ea2e4843a29e9854791bb5d93f
For the battle of El Alamein see https://www.history.com/topics/world-war-ii/battle-of-el-alamein#:~:text=Battle%20of%20El%20Alamein.%20The%20Battle%20of%20El,attack%20at%20El%20Alamein%20on%20Oct.%2023%2C%201942.