When Jason Stryker manifested his power to generate illusions at the age of five, William sent him to Professor Xavier in the hope that his son could be 'cured' of his mutation, but took him home when he realized that Xavier had no interest in 'curing' anything. A particularly vivid nightmare Jason had after returning home resulted in the deaths of his mother and older sister, resulting in William beating his son into submission and obedience. William took this as a "sign" from God and decided to make his "divine" mission to "purify" the world of mutants.
Joining up with Graydon Creed and the Friends of Humanity, they concocted a plan to force Superman and the Justice League to surrender their technology by holding hostage friends and relatives of the X-Men and X-Force members, and taking control of the Xavier Institute. General Stryker attempted to use the brainwashed Jason to try and trick Xavier into revealing Superman's true identity. However, Jason's efforts were thwarted thanks to the intervention of Miss Martian, and through the coordinate efforts of the League and the X-Men, their plan was ultimately foiled, and William was promptly arrested.