In the Kingdom of Prussia, often said to be an army which had a kingdom, as opposed to a kingdom which had an army, conscription was the rule of law for centuries. The same held true for other continental powers such as Tsarist Russia, France, the Habsburg Empire, et al.
The US was different. Conscription did not exist. Indeed, the very reason many young men emigrated to the United States from states like Prussia and the Tsarist Russia was to avoid conscription into the armies of those powers.
In the first one hundred years of the Republic, an appeal for volunteers always brought enough men to the ranks. Then came the Civil War. By 1863 the carnage of the war had dimmed the ardor of potential volunteers. Prior to the war, no one had foreseen in their worst nightmare the casualties which would be sustained on both sides.
According to the Congressional Research Service report: American War and Military Operations Casualties: 2,213,363 men served in the Union forces. Of those, 364,511 suffered death by cause of war which includes illness. (The Confederacy suffered approximately 250,000 deaths by cause of war.)
No wonder volunteers became hard to come by for the Union. So mandatory conscription became the law beginning in July of 1863. The reasons are complex but the white working men of New York City, upon whom the draft fell with great disappropriation, began to riot. A favorite target of the mobs were black men, thought to be competitors for construction jobs as well as the cause of the war. Dozens of African-Americans were lynched.
There was great destruction of property and upwards of 120 people killed, although the number remains in dispute. The riots came to an end when Federal troops with the dust of Gettysburg still on them, were brought to New York and opened fire on the mobs. While not letting historical accuracy get in the way of a good tale, the movie Gangs of New York, starring Leo DiCaprio explores this era. The movie seems long. The book its based upon, which has the same name, seems even longer. (3 stars for both but don’t run through traffic to see the movie or read the book.)
Gangs Of New York by Martin Scorsese and starring Leonardo DiCaprio, Cameron Diaz, and Daniel Day-Lewis
The Gangs of New York: An Informal History of the Underworld by Herbert Asbury