after two years of his providence revival, rees again took to the road to preach. with his boisterous preaching style, he was dubbed the "earthquaker." while in cincinnati, he met martin wells knapp. with knapp, rees formed the international holiness union and prayer league in 1897, an organization led by rees until 1905. the prayer league emphasized holiness, healing, evangelism, and premillennialism. in this regard, the league was heavily influenced by the “fourfold gospel” of a. b. simpson, founder of the christian & missionary alliance, which emphasized of salvation, sanctification, healing and the second coming.