Who is Sacco & Vanzetti from Howl, and Other Poems and what is their importance?

Nicola Sacco and Bartolomeo Vanzetti appear in the poem, America. They were Italian-born, American anarchists, who were tried and convicted for murdering a guard and a paymaster during the April 15, 1920, armed robbery of the Slater and Morrill Shoe Company in Braintree, Massachusetts. Both men were later electrocuted at Charlestown State Prison.