The PoD here is sometime in the 30s with a more hefty investment by the US into its defence industries (see Keynes Cruisers
for what I'm talking about). Something whose butterflies manage to fashion out into a better performing Allies in the 39-41 period, albeit not being enough to stop the Fall of France. The U.S enters WWII as OTL with embargo leading Pearl Harbour but Roosevelt dies of natural causes early in 42 and his successor Henry Wallace manages to throw a wrench into the Allied war effort. Torch goes off as OTL with allied forces managing to kick the Axis out of Africa by late 42 with the support of defecting Vichy forces under Darlan. This has the unfortunate side effect of leading to a half-cooked Allied Invasion of Europe in early 43 as a result of pressure from Wallace and Stalin (The Roundup/Sledgehammer Concept), the Western Allies manage to establish a toehold on Brittany but find themselves unable to sustain a foothold and are forced to withdraw by summer of the same year, leading to increased distrust between Longdon and Washington.
Germany meanwhile is doing slightly better on the Ost-front, Barbossa's early stages see slightly more success with the use of paratroopers and Rommel doesn't drag ~250k men and several Panzer divisions into North Africa. Nazi Germany avoids the encirclement at Stalingrad and spends late 42 to mid 43 holding out against a Soviet steamroller with a misfiring sparkplug and turns back the first allied assault into fortress Europe albeit at a heavy cost, especially in the air. Late 43 sees the Western Allies increasingly split their efforts with the UK and Commonwealth refocusing on the Med with an invasion into Sicily with the US building up for another invasion into Europe and ramping up lend-lease to the USSR.
44 and 45 see the Red Army finally gain its footing pushing back the Heer across the Dneiper while the Allied Airforce shatters German cities from above, an alt-Valkyrie* sends the Reich hurtling into all-out civil war as Italy defects and Anglo-American forces hit the beaches near Calais. The war in Europe ends with Berlin and eating a nuke and the Red Army meeting a mish-mash of Commonwealth, US, French and "Free" German forces farther west than OTL. Japan having had a less amazing run of luck across the Pacific and having been pushed back to home islands as OTL, followed suit after the appearance of mushroom clouds over Kokura and Hiroshima and the first Soviet troops hitting the beaches in Hokkaido. WWII Ends in early March of 46.
The post-war period would see an increasing American withdrawal inwards with an unpopular Wallace presidency leading to a conservative and isolationist backlash with the victory of Robert Taft in 1944. The post-war demobilization would see American troops rapidly depart Germany leaving in place a conservative authoritarian regime run by Carl Gordoeler and the alt-Valkyrie plotters and American economic support for a war-torn Europe dwindled to a trickle. Only in Asia would US troops remain principally thanks to the efforts of General Macarthur warily watching their Soviet counterparts across the Tsugaru strait and garrisoning "Free" Korea in Cheju.
Western Europe meanwhile banded together on the basis of "hang together or hang separately" with Britain, and Darlan's France* along with the Benelux and the parts of Germany under French and UK control forming the Western Union a combined NATO/EEC type organization. Non-communist Europe remains poorer than OTL a lack of an alt-Marshal plan and American investment drastically hampering recovery. Only Britain, having managed to avoid the humiliations of Singapore and less indebted to the US maintains a standard living close to OTL and has increasingly filled the hole left by the US in confronting Communism overseas.
*Darlan having managed to outmaneuver the alliance between De Gaulle and Giraud for control of the Free French
Iran came close to outright conflict with the USSR over the attempted installation of a friendly regime. After concluding that a puppet government in North would be a terrorism addled mess the USSR simply decided to spin off the Azeri and Kurdish bits as friendly puppets and went home, leading to an odd result of a left-wing nationalist regime allied to Britain taking power based on hating the Soviets even more.
The levant is less screwed up, with Palestine being chopped up into an internationalized Jerusalem and a larger West Bank Area and Gaza as part of a larger Kingdom of Trans-Jordan as part of a Anglo-American brokered arrangement. The presence of British forces prevented the Arab states from making a move, something which hasn't help Britain's reputation in the region.
American-Soviet confrontation took far longer to get started than OTL. With no real US presence in Germany, no Korean War and a more isolationist US public coupled with the fact that the USSR had taken even more casualties than and had less ability to compete at first helped keep things cool. Still, Stalin being Stalin things warmed as the Soviets and other Communist expanded their influence with the victory of the Reds in China and most of Indochina and the beginning of the Space race has caused a major stir. Talk of a "Cold War" or a new "Great Game" with the Soviets is becoming increasingly common even with the strengthened isolationist tendencies of the American public and political establishment.
Said sentiments are manifested in Africa and Southeast Asia where the French and British are embroiled in colonial and post-colonial conflicts against an array of insurgencies. France, in particular the generals who run the show, are deadset on holding onto the empire, the cost in both lives and material is increasing as is the public's willingness to send France's sons to die in distant shores.
The U.S is less paranoid about Reds compared to OTL, a bit more racist (there has been backlash following Wallace's rather hamfisted attempts at integration and the assassination of President Taft in 1950 by Puerto Rican nationalists), and the political spectrum has shifted leftwards with Dewey's six-year stint as President. Rock and Roll has emerged for all intents and purposes and the country is slowly reacquainting itself with global affairs, even if Joe Kennedy administration is more focused on battling scandal than anything to do overseas.
Things, however, are about to heat up. Whispers of change dance across lips in Parisian cafe's while Le Général discusses with sympathetic officers in smoke-filled rooms. In Egypt generals and officials review maps of the Suez, a paranoid Mao plans to purge the "traitors" before they purge him, while in Belgrade Tito returns from yet another unsatisfying meeting in Moscow and makes a phone call to Athens.
In the industrial cities of Northern Italy, militiamen count smuggled arms and ammunition. The Milan Commune is less than six weeks away.