Capwell Wyckoff 
In the Camp of the Black Rider [EPUB ebook] 

When Ted Thorn and Buck Dalton agree to lead the local Boys‘ Club summer camp, they expect the usual challenges of managing younger boys in the wilderness. But their leadership skills are put to the test as eerie happenings plague their remote campsite at Black Riders‘ Camp, named for Revolutionary War patriots who once gathered there. As tent ropes are cut, mysterious figures appear, and the woods are set ablaze, the two friends must protect their charges while unraveling the connection between a reclusive mountain man, a suspicious cabin dweller, and the camp’s Revolutionary War history.