https://archive.org/details/youngcrusadersst00atwa
The young crusaders; the story of a boys' camp
by Atwater, George Parkin, 1874-1932
Boys own story. A group of friends who play football, go camping, and solve mysteries
Theres also a follow up,
https://archive.org/details/youngcrusadersat00atwa
The young crusaders at Washington
by Atwater, George Parkin, 1874-1932
The young crusaders; the story of a boys' camp by Atwater, George Parkin
Carolin