Answer:
Starvation/Famine
Explanation:
As the population boomed in Russia in the late 1800s and early 1900s, the serfdom found itself unable to feed itself, the nobility, and the clergy, as a result the Russian people started the Red October, which eventually saw the fall of the Russian Empire and the Rise of the USSR.
If you've been assigned a research paper on the Holy Wars, then an "Encyclopedia" would provide a factual base for additional research, since it is the most reliable.
The slaves were promised freedom if they fought for the British. It is known that Black men enlisted at a higher rate than white men. Most free blacks fought for the Patriots.