The series was based largely on Alexander Rose's book Washington's Spies: The Story of America's First Spy Ring, describing the activities of the Culper Ring during the American Revolution.

While the basic details are accurate, they took dramatic license with characters and how events transpired. There is no historical evidence that Abraham Woodhull and Anna Strong were romantically involved like on the show, among other inaccuracies. He wasn't married while in the ring either. (Benedict Arnold's arrogance and huge ego, however, were well-known in real life -- on both sides of the war -- and are pretty much spot-on in the show.)

A show about the American Revolution on a US network was likely going to depict the British as the "bad guys", and while some of the Redcoats get more sympathetic treatment, none suffered the level of historical misrepresentation than John Graves Simcoe, commander of the Queen's Rangers, did. If he were alive, he could sue them for libel. It was tantamount to a character assassination. They could have just changed his name if they wanted to play fast and loose with his character.

I get that all dramas need villains, and the Rangers were among the most successful Loyalist regiments in the war. As a scourge of the Patriots, this was historically accurate. But this was where the history ended. Simcoe was a capable and skilled officer, but the series portrayed him as an often insubordinate, vile and unstable psychopath. Hard to believe when, in reality, he would later go on to become Lieutenant Governor of Upper Canada. The series tried to circle back to his historical fate in the final season, but after three seasons of vilification it was a moot point. They did allude to his abolitionist tendencies on the show when he freed a slave who joined the Rangers. Many slaves were offered freedom to fight for the British cause during the revolution.

The American Revolution was in essence a civil war where neighbours, families and friends were divided between Tories (Loyalists, or King's Men) and Patriots. The show alluded to this in the Woodhull family, where they portrayed Abe's wife and father as initially Loyalist. But the show didn't delve much into these divisions, which ripped apart entire towns and regions during the war.

The problem with historical accuracy on a show like this is you never know how many sources they relied on when they did their research. It seems they relied too heavily on Rose's book. Had they done enough legwork on Simcoe -- he wrote a journal of his activities during the revolution -- they might have given him a more balanced portrayal.

The series was entertaining as a show if you're interested in the Culper Ring and the revolution, and their version of Simcoe was indeed a 'villain' you could love to hate, but as a source of historical accuracy TURN needs to be taken with a grain of salt.