That they would take control of the world
Japan had been antagonizing the Chinese by executing rigorous military operations near the Marco Polo Bridge in Beijing. One night, a small troop of Japanese soldiers demanded to enter a tiny walled town. The Chinese refused. A shot rang out and a Japanese soldier was killed. A full-scale war between Japan and China would soon follow.
One of the greatest atrocities committed by Japan was after the fall of the city of Nanking. The Japanese Imperial Army raped and murdered more than 10,000 Chinese.
The blacks would be happy that the Union were winning because they were one step away from freedom from slavery
The Russian revolutionaries wanted something more than famine and injustice -- and that's much of what existed in Russia at that time. They wanted equality for all persons. That was a big goal of the communist agenda, and the Russian Revolution was a communist endeavor. They wanted to achieve that equality both in terms of wealth/property and in terms of political status and rights.
Was it dangerous? Absolutely. The reign of the tsars had gone on in Russia for centuries, and military victory over the tsar's armies had to be won for the revolution to succeed. And it was not going to be easy to make the nation better off, even after the revolution. The people would expect results from the new government. Those results were going to be hard to achieve.
Over time, the Union of Soviet Socialist Republics (USSR), which was the nation brought about by the Russian Revolution, has to become more and more authoritarian and repressive to keep its agenda going. And eventually that agenda failed, when about 75 years after the revolution, the USSR's government collapsed.