FORT EDWARD, N.Y. (AP) – Wish the U.S. Army Rangers happy anniversary.

It was 250 years ago Thursday that a colonial American officer from New Hampshire sent a letter to his British superior listing 28 rules for ranger companies fighting against the French and Indians.

Maj. Robert Rogers wrote his ranger rules on an island at Fort Edward, a British outpost on the upper Hudson River. “Ranging companies” were nothing new at the time, having been used in the English colonies for decades. But the frontiersman is credited with being the first to write a guideline for waging guerrilla warfare in the North American wilderness.

Known as “Rogers’ Rules,” they’ve since been boiled down to 19 that are still used today by U.S. Special Forces, including Green Berets and Army Rangers.

This weekend, former Rangers are expected to join French and Indian War re-enactors in Fort Edward for ceremonies marking the 250th anniversary of Rogers’ Rules.