Daniel was one of the first popular heroes in the US, a famous hunter and pioneer that explored forests occupied by Indians in the XVIII century. He was considered a legend while living, especially after one of his adventures was published as a tale in 1784, which made him notorious in the United States, as well as in Europe! Though much of his life is remembered with a lot of historical mistakes, he is most known for his explorations and settlement constructions in Kentucky. He also fought in the American Revolutionary War (1775 - 1783) and was captured by Shawnees in 1778. Boone was accepted to become a member of the tribe, but chose to escape to continue fighting to defend the Kentucky colonies.
As for his famous "raccoon" hat, I couldn't find precise information whether it was real or just part of his legend. I'd totally wear one of those, though!