Chapter 5.5: World War II
While the focus of this narrative is the Communist Party of China's War of Liberation against the enemies of the people, the international situation in Europe during the late 1930's cannot be ignored. China could not be truly unified until Japan's grasp over Manchuria was removed, as well as the large French, Portuguese, and British concessions in Guangdong and the other concessions located in Shanghai and Tianjin. Due to the strength of the imperialists, Mao and the CPC knew that China alone could not face the Europeans and the Japanese. Outside help was essential, and that aid was to come from the Soviet Union. With the USSR having been soundly beaten by Japan during the two short border skirmishes, the resulting NAP between the two major powers moved the USSR's attention to the west.
On September 1, 1939, after months of threats and belligerent negotiations, Germany declared war on Poland. Emboldened with its earlier diplomatic successes, Germany felt that the weak capitalist societies would cave in to the threat of a new global war and not follow through on the Entente's guarantee of Poland's borders. However, the capitalists were not bluffing, and France and the British Commonwealth responded to Germany's declaration of war with their own. At the time, many Europeans believed that the war would be short and limited in scope. Afterall, Germany wasn't the only nations with claims on Polish territory. The Soviet Union, shortly after its birth lost large portions of Belarus and Ukraine to Poland during the 1919-1921 Polish-Soviet War. Lithuania's ancestral capital was also held by Poland. As Germany hadn't negotiated any formal non-aggression pacts with either Lithuania or the Soviet Union, the theory of Germany limiting the war with Poland to reclaiming Prussian land lost after 1918 became more credible. Surely Germany wouldn't risk another two-front war?
As such, everyone observing the situation was stunned when Germany forced Poland's unconditional surrender and full annexation after only 13 days of combat. According to the CPC ambassador in Moscow, Stalin was outraged when he heard news of Germany's attack. Apparently negotiations to split Eastern Europe into Soviet and German spheres of influence were nearly completed when Germany attacked and annexed Poland. With the Entente, as the Allies were called upon the start of the war, busy fighting Germany's western defenders and Germany unlikely to intervene, Stalin issued an ultimatum to 3 of the 4 Baltic States. Lithuania, Latvia, and Estonia were to rejoin Mother Russia and become Soviet Republics inside of the USSR. On September 4, the 3 nations caved in to Soviet pressure and relinquished their short-lived autonomy.
Three of the four Baltic states relinquished their autonomy in the face of Soviet might
At this point, an already chaotic situation began to spiral completely out of control. On September 17, Japan joined the Entente as it did 25 years earlier to contain German aggression. Japan had a vested interest in seeing Germany's demise, as Germany was the #1 buyer of tungsten from China and top supplier of weapons and military trainers to China. Defeating Germany would indirectly aid Japan in any future aggression in China. Japan's entry into the alliance between France and the United Kingdom worried not only Mao, but the KMT leadership in Nanjing as well. Any future attack on Japan would also bring in Japan's new allies, and any Japanese attack upon China would bring the imperialists back to China in order to secure more concessions.
Japan joined the Allied Powers on September 17, 1939
On September 27, Stalin once again applied pressure to the USSR's weaker neighbors in an attempt to regain land lost during the Russian Civil War. This time his target was Romania. The Ukrainian SSR had lost the region of Bessarbia to Romania, and now that the Soviet Union's greatest potential enemy was involved in a war against the capitalists, Stalin felt he held the upper hand in any negotiations with nations that held land that was rightfully part of the Soviet Union. While Germany had good relations with Finland (as a buffer against the USSR) and Romania (the main source of German fuel), it could not afford to antagonize the USSR for fear of another 2-front war. As such, Romania not only agreed to Stalin's demand for Bessarbia, but his demand for North Bukovina as well, which was formerly part of the Austro-Hungarian Empire. Of note is that the Red Army hadn't yet mobilized to deal with any serious fighting. Stalin felt the Red Army's mere presence was enough of a threat to force his way diplomatically as well as deter any German aggression.
Romania cedes its north-eastern most territory to the USSR in order to avoid war
However, Romania's fate was not yet sealed, as Hungary also had claims on Romanian-held Transylvania, which had off-and-on been a Hungarian possession since the 9th century. With German support, Hungary demanded that Romania cede the majority Magyar northern portion of Transylvania to Hungary. With Hungary having been stripped of its former power due to the Treaty of Trianon and Germany being occupied, Romania refused Hungary's demands. With Germany already stretched with substantial forces along the new Soviet/German border to discourage a Soviet attack and along the German/French border to prevent French offensives into Germany itself, Hungary was left alone to enforce its claims. Due to Hungary's poor situation, the country had no chance to force its claims upon Romania, and gave up on September 27.
Hungary fails in its bid to peacefully reincorporate ethnically-Hungarian Transylvania
As Europe spun further into chaos, Hitler apparently thought the situation was too calm, and on October 9 Germany declared war on the Soviet Union. Even before his imprisonment in 1924, Hitler had publicly committed to a policy of racism and eastward expansion. In his many speeches and written works, he had declared the Soviet Union to not only be the enemy of both the capitalists and national socialists, but the location of Germany's future "living space". Many thought his rants were focused solely upon gaining more votes for his party. However, on October 9, 1939, Hitler once again plunged Germany into a two-front war, but did so this time on ideological grounds. While the attack was strategically a poor choice, since two of the three nations that brought Germany to its knees in 1918 still existed to the west and now had plenty of time to strengthen themselves, from a tactical level Hitlers decision was sound. The Red Army wasn't fully mobilized, was poorly trained, was poorly led, had a large front to defend, and the USSR had many raw materials that Germany lacked. In the long-term, Germany would lose any war it engaged in due to lack of natural resources. Defeating the USSR quickly while holding the French and British at bay would secure the necessary resources for Germany to defeat its capitalist foes.
Germany once again willingly starts a 2-front war
The next day, October 10, 1939, the UK and USSR partition Iran amongst themselves. Once the war began, the Shah of Iran had expressed sympathy to Germany's situation and had begun to sell oil to Germany at discounted rates. At the time, the British oil company BP had near monopoly drilling and refining rights in Iran. The Shah bypassing BP's monopolistic authority threatened oil shipments to the UK. At the same time, the Soviet Union had a desire to use the Trans-Iranian Railway to ship Allied support directly to the Soviet Union, bypassing the long route from Vladivostock and the treacherous routes through the Baltic and White Seas. The result of the occupation was the USSR annexing the southern shore of the Caspian Sea and the UK installing a cooperative puppet regime in Tehran.
Iran is occupied by the USSR and UK for the dual purposes of increasing Allied support and safeguarding UK oil sources