He was given command of a company and marched to Cambridge, Massachusetts and became part of the Army of Observation in support of the rebellion against British rule.

In September 1775, George Washington put Major Greene in charge of a battalion in Cambridge under the command of Colonel Benedict Arnold.

In October, Greene was in charge of Fort Mercer near present-day Deptford Township, now National Park, New Jersey, south of Philadelphia and Trenton in Gloucester County.

Though they were supported by gunfire from six British men-o-war in the Delaware River, they were repulsed with heavy loss, and von Donop was mortally wounded.

When the idea of offering slaves their freedom in return for active service was first suggested, all concerned believed the plan would help solve the problem of finding Continental recruits.

The Rhode Island General Assembly voted that every able-bodied Negro, mulatto, and Indian slave could enlist for the duration of the war with bounties and wages the same as for free men.

General Sullivan, whose headquarters were in Providence, was charged with the task of containing the depredations of the 4,000 British and Hessian troops occupying Newport on Aquidneck Island.

In early July 1778 orders from General Washington changed Sullivan's mission from defense to attack and thrust the quiet Rhode Island sector into the forefront of the war.

[4] Colonel Greene and Major Ebenezer Flagg, along with six black soldiers, and two others who later died of their wounds, were killed on May 14, 1781, when a group of loyalist insurgents, known as the Royal Refugee Corps under the command of Lieutenant Colonel James De Lancey, surrounded Greene's headquarters on the Croton River in Westchester County, New York.

A fine portrait of Colonel Greene by James Sullivan Lincoln hangs in the John Hay Library of Brown University in Providence, Rhode Island.