Nicola Sacco was born in the Italian town of Torremaggiore on 22nd April, 1891. He emigrated to the United States when he was seventeen. Sacco found work in a shoe factory in Stoughton, Massachusetts. He got married and started a family. Sacco also became involved in left-wing politics and at one anarchist gathering met Bartolomeo Vanzetti, an Italian immigrant working as a fish peddler in Plymouth. The two men became friends and often attended the same political meetings together.

Like many left-wing radicals, Sacco and Vanzetti were opposed to the First World War. They took part in protest meetings and in 1917, when the United States entered the war, they fled together to Mexico in order to avoid being conscripted into the United States Army. When the war was over the two men returned to the United States.

On 5th May, 1920, Sacco and Bartolomeo Vanzetti were arrested and interviewed about the murders of Frederick Parmenter and Alessandro Berardelli, in South Braintree.