Greene willingly gave much of his personal wealth to help support the war, even sacrificing his Rhode Island home. To thank him for his service during the war, the Georgia government gave Greene a plantation named Mulberry Grove, outside Savannah in Chatham County. He lived on the Mulberry Grove estate for less than a year, troubled by insecure finances; the plantation did not become profitable. Greene died unexpectedly of sunstroke in 1786, at the age of forty-four. Greene's remains and those of his son, George Washington Greene, lie beneath a monument in Johnson Square in Savannah.
After Greene's death, a young Yale University graduate, Eli Whitney, came to Savannah to take a tutoring job. Whitney began working for Greene's widow, Catharine, and it was at Mulberry Grove that Whitney invented the cotton gin, the machine that revolutionized the production of cotton.
In fact, Whitney met Mrs. Greene on a ship from Rhode Island to Georgia when he was moving to take the teaching job and she was going to remarry. They struck up a friendship, and when he discovered that the pay for the teaching job was half what he had been promised, she offered to let him live at Mulberry Plantation while he decided what to do next.
At Mulberry Grove, much of the evening conversation was about the difficult economic situation plantation owners faced. At that point in US history, slavery was a dying enterprise. Slaves were expensive to keep and there was little profitable work for them to do. The market for local crops, indigo and rice, would not support large plantations, and though growing cotton was a possibility, it was too expensive separating the cotton seeds from the fiber to make the crop profitable.
A few days later, Whitney was in the plantation barnyard watching a cat try to catch a chicken through a wire fence. Each time the cat would reach through the fence for the chicken, all he would bring back was a paw-full of feathers. This lit the bulb in Whitney's imagination and he realized that folks were trying to solve the wrong problem with cotton. The solution wasn't separating the seeds from the cotton fiber, it was separating the fibers from the seeds. He devised a screen-wire basket in which a roller with small picks would pull the fibers through the screen leaving the seeds on the other side. This became his Cotton Engine and was an immediate success throughout the cotton-growing regions of the south. This drove a huge demand for field labor in Georgia, Alabama, and Mississippi and lead to a great transfer of slaves from Virginia and the Carolinas, greatly upsetting slave families and leading to the upheaval that lead to the Civil War some sixth years later.
Had Whitney not seen that cat, who knows what would have happened in American history. This is why a cat should be credited with starting the Civil War.