1941-1943, Japanese-American war
Though the German Führer Adolf Hitler had postponed the invasion of Poland to 1944, he still kept his alliance with Italy and Japan strong. Hoping that if they were threatened with war across the planet, the allies would not go to war, Hitler, Mussolini, and Tojo signed an agreement where they would come to each other's aid if they were attacked.
This was signed in 1940, and two years later, on December 7th, 1940, Japan bombed Pearl Harbor, and invaded the Philippines, Burma, Malaysia, and Indochina. America declared war on Japan, though Britain and France still didn't want war, so allowed the Japanese to take the colonies, believing that it was better to stay at peace then risk war.
However, the German and Italian Governments fulfilled their promises to Japan. Declaring war just days later, Germany and Italy were now at war with America. America asked for British and French assistance, though the two of them stayed neutral, leaving America to stand alone.
The non-aggression pact between Russia and Germany held, though tensions were still strong. The US Atlantic fleet fought several battles in the Atlantic against the German navy. Germany still never committed all of its large warships, preferring to commerce raid with battle cruisers and U-Boats.
This led to skirmishes between the two navies. Aside from this, no other large warfare occurred. In the pacific the Australians entered the conflict, joining the US in its war against the Axis. Now with another important part of its empire threatened, Britain had a choice.
Winston Churchill voiced his opposition to Anglo-French Neutrality, and began a campaign to whip us support for war. German and American warships meet in battle off Norfolk Virginia, where American aircraft carriers win the day against German O-Class Battle cruisers. Germany loses three of its four Graf Zeppelin aircraft in the battle, to one US Essex-class. October 1942 proves to be quite decisive for the Americans, and the Germans no longer launch fleet actions against the US.
Nevertheless, Hitler decides the time to strike is now. In a surprise offensive, German tanks and men charge into France, Luxembourg, Belgium and Holland. Holland and Belgium are crushed within days, while Luxembourg offers no resistance and is occupied within a day.
French tanks are deployed peaceably in infantry support, in contrast to the Armored Fist of the German offensive. German tiger tanks prove to be decisive, and the German invasion of France is just as devastating as in our timeline.
The German army is able to cut the allied line in two by May 25th, and the British and French armies are pushed to Dunkirk. The German army prepares for a decisive battle, though its tanks and men are exhausted from the long fighting and rest, allowing two British and one French army to escape.
Nevertheless, German forces retain the initiative by June 1943, and bombing raids and air attacks on British cities by German jets prove devastating. The German air force pummels the RAF day and night, though it continues to hold out. German and British battle fleets meet in battle off Scapa Flow. Superior German H-Class Battleships and U-Boats defeat the British fleet, which flees to the US.
With the allies in Europe collapsing, Germany launches a final drive on Paris, capturing the city with virtually no resistance by June 10th. French morale drops as the Germans attack the Maginot Line from behind, which culminates in the French surrendering by the 12th.
The German army's victories are short lived as US troops land in Britain, alongside B-17s. They counterattack into German cities, bombing them from the air. German and US fighters fight a continuous Air Battle, while German troops execute a cross channel invasion of Britain.
The experienced US army leads a successful counterattack in southern Britain. From September to November 1943, German forces fight the allies in Britain. The US navy fights several battles, using aircraft carriers to their advantage, succeeding in defeating the German fleet off Jutland, and blockading the British coast.
German forces are pushed back and are surrounded in Dover. The German commander, Colonel General Von Paulus surrenders.