This is a pretty cool story. My aunt found it in an old family history book about one of my relatives. The claim was that he nearly killed George Washington in battle and that after missing his point blank shot an American soldier intervened and was about to kill him. The claim is that he flashed a Masonic sign to George Washington and that because of this Washington told the soldier to spare his life and insisted that he be taken in as a POW. The story continues that Washington came to visit him and ensure he was being treated properly. The last name of my ancestor was Darley if this helps at all.
I know that verifying the story itself would be difficult but in particular is there a history of soldiers of opposing sides of the American Revolution sparring one another because they were both Masons?
There's a more detailed account of the incident here: http://www.lasersol.com/history/thomas_darley.html
The page draws the story from "Your Darley Ancestors" by Lon J Darley, published in 1979. I don't have access to that work.
However, there is an older account of Mr Darley's escape:
"The History of Methodism in Georgia and Florida: From 1785 to 1865" By George Gilman Smith (1877), page 71, we find:
"Samuel Cowles, another Virginian, who was to do much work for the Church in Georgia, came this year to the State. He had been a dragoon with Washington's Light Horse. In the battle of Cowpens he swept down with upraised sabre upon a British Trooper, whom he disarmed, and was about to cut him down. The trooper gave him the Masonic signal of distress, and he spared his life. Years after, he met his old foe in Thomas Darley, a brother-in arms, in the South Carolina Conference."
Note the George Washington is not involved in this version, a hundred years closer to the event.
I'm a Mason, and I do actually find this plausible. There are other sources on how Masonry was involved in both the Revolutionary and Civil Wars, but I'm at work and don't have access at the moment.