Available from ABEbooks:
https://www.abebooks.com/servlet/BookDetailsPL?bi=22833911499&searchurl=tn%3D%2522camp%2Bof%2Bthe%2Bsaints%2522%26sortby%3D17&cm_sp=snippet-_-srp1-_-title1
If it truly IS Public Domain, that is a publishing opportunity for somebody.
Ooops. More than one book with that title. I don’t see how a book that recent would be public domain. You need the one by Jean Raspell.