President Abraham Lincoln had first asked for volunteers to join the military to help the Union. After the first Battle of Bull Run took many Union soldiers.
As the Civil War went on there was more of a shortage of manpower in the Union. So to resolve this problem, Congress passed the first Conscription Act in 1863. Allowing citizen men 18 years of age to be drafted in times of war.
Even though at that time the draft was designed to start voluntary enlistment and actually very few men were drafted into service.
Most of the Democrats in New York City were known as Copperheads and they objected to national service of any kind. These Copperheads wanted provisions for their elite that allowed them to pay either $300 or supply a substitute as a commutation fee. This led to the term "300 dollar man and clubs were formed to help supply the commutation fee. Similar to draft-dodging and the public middle to lower class thought that the war had become "a rich man's fight".
The first drawing of names were mainly of mechanics and laborers whose names previously appeared in newspapers. Although the NY City riots had not started then, other riots did occur in Buffalo, NY.
The second drawing was held on July 13, 1863, 10 days after the Battle of Gettysburg was won by Union forces, a furious crowd ripped through the streets of NY City and no New York State Militia was sent because they were with Union troops in Pennsylvania.
The Democratic Party/Copperheads of Tammany Hall wanted to make Irish immigrants as citizens to vote in local elections. Many new poor Irish immigrants soon found out that they had to fight for their new country and that helped fuel the riot by many immigrants. Many immigrants viewed freed slaves as competition for the few jobs offered.
Also many Americans blamed blacks/African Americans as the reason for the Civil War to begin with and so an angry mob began to vent their anger on all or any blacks found and even went in search for some to slaughter their frustrations upon.
The riots stopped after word was sent to suspend the draft. The exact death toll during the New York Riots is unknown but historians wrote that NY Riots were equivalent to a Confederate Victory. Then several thousand Federal troops entered the city for the next drawing on August 10 and riots had ceased. Many Democratic wanted to have the draft declared unconstitutional but the Tammany Hall Democratic did not declare the draft unconstitutional but did help pay commutation fees on behalf of poor who were drafted.