On September 1, 1939, the Third Reich invades Poland and two days later the British and French declare war. On September 17, 1939 the USSR invades Poland and the Allies view this as pure aggression against Poland and so war is reluctantly declared on the USSR. Stalin is surprised but is not upset and conceives a plan to take his share of Europe as with Germany he thinks the Axis can be unstoppable but is upset though that now Japan is his ally in some way.
After the surrender of Poland, a period known as the Phony War begins as nothing happens and mobilization occurs among both alliances. In the meantime, Hitler and Stalin work out a deal that would give the USSR the following areas of Europe; Eastern Poland, the Baltic States, Bulgaria, Romania, Finland, and part of Greece. Hitler will receive the other half of Poland, Denmark, Norway, the UK, France, Yugoslavia, Slovakia, Hungary, the Benelux Countries, Albania, most of Greece, and Italy. Though the Third Reich has an alliance with Italy, it will invade Italy and put Mussolini possibly in the middle as he would have two sides against him, that being Mussolini of course.
The Winter War occurs and in this timeline the USSR conquers Finland with Nazi help. Sweden feels threatened so it signs a neutrality pact with both Axis Powers and promises economic help if needed and some supplies of iron ore.
In a surprise attack, the USSR invades Romania and shocks the world. This war will last into 1940. Germany meanwhile is preparing to march into the west as their troops are gathered while the Soviets aggravate the world.
In early 1940, the Romanians surrender and the Soviets march further by invading Bulgaria and taking the nation by March of 1940. In April the Germans invade Norway and Denmark and by May the two nations have surrendered. In May of 1940 the Germans march into the Benelux Countries while the Soviets head into Greece to expel the British from the Mediterranean. Another POD in this timeline is that the enigma code is never broken and the German Navy runs amuck in the Atlantic and North Sea and a much quicker defeat of Norway is achieved since also the Soviets get involved and claim the northern areas of Norway.
Meanwhile the Soviet Union has been struggling to take Greece but have taken the Baltic Region and rumors spread that Italy may join the Allies in fear of a Nazi-Soviet-dominated Europe. Germany makes Mussolini decide when he issues an ultimatum demanding whose side he is on. Italy doesn’t respond and so Germany begins a small invasion of Northern Italy from Austria. In May the Benelux Countries fall and the Battle of Dunkirk occurs in France. In this timeline the Nazis do attack and the resulting chaos is the destruction of the Allied Army, Royal Navy, and Royal Air Force but the RAF does somewhat survive. On June 21 the French surrender and so it appears the Nazis and Soviets will dominate the Earth.
In Greece the Soviets make gains and by July Athens has fallen and the Greeks and British flee to neutral Turkey. In July the Third Reich has Hungary and Slovakia join the Axis and Albania is put into the Soviet sphere of influence as is part of Yugoslavia. The Battle of Britain is also begun as preparation for the Invasion of Britain or Operation Sea lion. As Europe falls under the Axis Powers, the Invasion of Italy is expanded as the Germans launch a massive invasion of the country from France and Austria. Italy falls by August and Yugoslavia is invaded in mid-August. Meanwhile the Battle of Britain is going well for the Axis as the RAF is devastated and Operation Sea lion is set for September 15.
On September 15, Nazi forces land on beaches on the British coast but heavy resistance is met but because of the Luftwaffe having air superiority, British troops have a hard time holding the Germans and Churchill gives orders allowing for the use of chemical weapons. Fear spreads amongst Britons when word spreads that the German nuclear program is doing well since British agents weren’t able to damage the project. After the primary objectives are reached the Germans offer peace but the Brits refuse and the Germans promise total war. The Royal Family and most of the government is evacuated to Canada safely. Churchill though stays even though he flees to Edinburgh. The Germans march further into England but when the German Army nears London, British troops use tear gas and mustard gas on the Nazi troops. The frontline stalls for days but quickly resumes and by October the Germans are in London but street fighting is slowing them down. This convinces Churchill to flee to America.
Throughout October and November, the Nazis battle for London and finally take it and the British surrender before it is too late. The United Kingdom falls and Ireland joins the Axis. Iceland and Greenland are then invaded by American troops as a safety net for North America. In Yugoslavia the war ends and Europe falls under the Axis but Gibraltar remains British and Albania hasn’t joined the Axis or been invaded so the Soviets invade Albania and Germany convinces Spain to go to war and Portugal then joins the Allies. By December the Axis have conquered Portugal and Albania. As Europe heads into 1941, Switzerland worries as German forces increase around the border and even Sweden begins to fear the Axis. In the US, FDR wins by less than one percent and begins to worry how he will be able to help if America itself doesn’t trust him in office.
As the Soviets and Germans get greedy, the Soviets launch a surprise invasion of Sweden and Hungary and Germany is very upset but is almost afraid to do something because they believe the Soviets will be a key ally for now. In another shocking move, the Nazis invade Switzerland and even more surprisingly, Spain, an ally of Germany. The Soviets now also become secretly worried about their ally but since both Stalin and Hitler have a mutual fear of each other, both will use their alliance to the best of its ability.
As the UK becomes a puppet of Germany, forces are built up and operations prepared but the wars in Sweden, Hungary, Switzerland, and Spain are at the world’s attention. Slovakia is secretly annexed by the Nazis while the world is unable to notice. By the end of the year, all of Europe belongs to either Germany or the Soviet Union but another development puts Europe back in the war.
Japan attacks the United States of America on December 7, 1941. Germany and the Soviet Union declare war on the United States. Now it becomes a true world war. Germany meanwhile prepares its fleet for a massive Battle of the Atlantic. One of the Nazis first goals is to secure the seas and conquer Iceland and Greenland from the Americans. The Soviets and Japanese will handle the Pacific.
As the Soviet Union fell out of the European picture the Germans gathered there forces for the massive invasion of Iceland. By spring the Germans have damaged American ships severely and now launch the invasion of Iceland. After an eight-month campaign the Nazis capture the important island and days after the United States builds up forces in Greenland and the arctic island becomes one massive military base. 1942 is the preparation year for the Great Battle of Greenland.
At sea the Nazis begin a move to North America and convince Argentina to join the Axis. Brazil then joins the Allies and soon South America chooses sides. Mexico, Argentina, Bolivia, Paraguay, Nicaragua, Honduras, and Uruguay join the Axis while the rest join the Allies. Germany invades Greenland in February and the grueling campaign begins. In South America, the Axis are making fast gains thanks to German and Soviet supplies getting to the ports as Africa was taken by the Germans but is still being fought for. The United States becomes a battleground as the Mexican Army attacks the Southwestern US. By May the US Army has been able to push most of the Mexicans out but has to hold ground in Greenland or face a possible invasion by Germany in the near future so some ground is lost when some troops are moved to Greenland. In July the Battle of El Paso and the Battle of Godthab are two of the bloodiest battles of the war. In El Paso the Mexicans continue to fight until the last man and only a few survive on the Mexican side and on the American side there are plenty of dead. The battle is an American victory but came at a very high cost. In Greenland the battle lasts most of July and thousands die as bombs and bullets fly everywhere. The city is destroyed and the Americans are caught off guard when German troops encircle the city and German U-boats blockade the city. The Americans surrender and Greenland falls by September when the last American leaves the island. The American Navy then begins massive production of new ships and is prepared along the entire Atlantic Coast of the Americas for an invasion of somewhere but it is expected that the Canadians will see the Nazis first. The Soviets meanwhile begin to threaten Alaska. In November the Nazis begin preparation for Operation Sealion II, the invasion of Canada. 1943 ends with the Axis ready to take away everything throughout the world.