American general, son of a Quaker farmer and smith, was born at Potowomut, in the township of Warwick, Rhode Island, on August 7 (not, as has been stated, June 6), 1742. At Coventry, RI, where he went in 1770, he was the first to urge the establishment of a public school. In the same year he was chosen a member of the legislature of Rhode Island, to which he was re-elected in 1771, 1772 and 1775. He sympathized strongly with the Whigs and in 1774 joined the local militia. At this time he began to study the art of war. His zeal in attending to military duty led to his expulsion from the Society of Friends.

In 1775, in command of the contingent raised by Rhode Island, he joined the American forces at Cambridge, and on June 22 was appointed a brigadier general by Congress. To him General Washington assigned the command of the city of Boston after it was evacuated by British General Sir William Howe in March 1776. On August 9, 1776 he was promoted to be one of the four new major generals and was put in command of the Continental troops on Long Island, but severe illness prevented his taking part in the battle of Long Island. Greene was placed in command of Fort Lee, New Jersey, and on October 25 succeeded General Israel Putnam in command at Fort Washington. Greene ordered Colonel Magaw, who was in immediate command, to defend the place until he should hear from him again, and reinforced it to meet General Howe's attack. Nevertheless, the blame for the losses of Forts Washington and Lee was put upon Greene, but without his losing the confidence of Washington, who assumed the responsibility. At Trenton Greene commanded one of the two American columns; he commanded the reserve at Brandywine, and was prominent in the battle of Germantown, though his troops arrived late.

At the request of Washington, on March 2, 1778, he accepted the office of quartermaster general (succeeding Thomas Mifflin), and succeeded with it as well as anyone could under the circumstances, meanwhile continuing to command troops in the field. In August he resigned the office of quartermaster general, after a struggle with Congress over the interference in Army Administration by the Treasury board. On October 4, 1778, he succeeded General Horatio Gates as commander-in-chief of the Southern army, and took command at Charlotte, North Carolina, on December 2, 1778.

The army was weak and badly equipped and was opposed by a superior force under British General Charles Cornwallis. Greene decided to divide his own troops, thus forcing the division of the British as well. This strategy led to General Daniel Morgan's victory at Cowpens, South Carolina, January 17, 1781, and to the battle at Guilford Court House, North Carolina, March 15, in which after having weakened the British troops by continued movements, Greene was defeated indeed, but only at such cost to the victor that Tarleton called it "the pledge of ultimate defeat." Three days after the battle at Guilford Court House, Cornwallis withdrew toward Wilmington, North Carolina. Greene allowed Cornwallis to march north to Virginia and then turned swiftly to the reconquest of the inner country of South Carolina. This, in spite of a reverse sustained at Lord Rawdon's hands at Hobkirk's Hill (April 25) he achieved by the end of June, the British retiring to the coast.

Greene gave his forces a six weeks' rest, and on September 8, with 2,600 men, engaged the British under Lt. Col. James Stuart at Eutaw Springs; the battle, although tactically drawn, so weakened the British that they withdrew to Charleston, where Greene penned them during the remaining months of the war. Greene's Southern campaign showed remarkable strategic features that remind one of Turenne, the commander whom he had taken as his model in his studies before the war. He excelled in dividing, eluding and tiring his opponent by long marches, and in actual conflict forcing him to pay for a temporary advantage a price that he could not afford.

South Carolina and Georgia voted Greene liberal grants of lands and money. In 1785, after twice refusing (1781, 1784) the post of Secretary of War, he settled on an estate, Mulberry Grove, 14 miles above Savannah. There he died of sunstroke on June 19, 1786.