In the late 1830s, Captain Obed Marsh founded the Esoteric Order of Dagon in the Massachusetts town of Innsmouth combining Holy Scripture, Middle-Eastern fertility worship, and Polynesian rites. In 1846, a strange disease wracked Innsmouth. When villagers from nearby communities investigated, they found half of the town’s people dead, and Obed Marsh and his Order in complete control.
Degenerative traits began to surface in the children of Innsmouth, blamed on the plague, but actually caused by interbreeding with the nearby colony of Deep Ones, as dictated by Marsh’s Order. All of Innsmouth’s churches were converted or closed. The town became shunned by the surrounding villages, and the Marsh family maintained its deathgrip until the Order's destruction at the hands of the federal government (see Project COVENANT).
Other branches of the cult may still secretly exist. These should not be confused with a real-world small amateur press club or a defunct group of Lovecraftian magicians who have both used the name.
Written by Raymond H Rich, based upon material given in Delta Green by Adam Scott Glancy with John Tynes, The Encyclopedia Cthulhiana by Daniel Harms, Arkham Horror by Richard Launius, Lynn Willis, and Charlie Krank, "The Shadow Over Innsmouth" by H.P. Lovecraft, and Escape from Innsmouth by Kevin Ross.