General Information
Symbol of Dagon.
The Esoteric Order Of Dagon was a cult that was based in the town of Innsmouth, Massachusetts from the 1840's until the 1920's.
For decades, the Order virtually controlled the town.
Foundation
Soon after Obed Marsh brought the Deep Ones to Innsmouth, they forced the town to give them human women to mate with. This led to the birth of the Innsmouth hybrids, as they came to be called.
It was at this point that Marsh founded The Esoteric Order Of Dagon which was a cult composed of himself, his followers, the Deep Ones, and, in time, the Innsmouth hybrids.
The Order subsequently evicted the Freemasons out of their Innsmouth headquarters and took over the building themselves.
The Order in Innsmouth
Over the following decades, the Order more or less had de facto control of Innsmouth. They controlled all the major businesses, the town council was made up of their members. All other religions were gradually pushed out of town. Anyone who opposed the Order was either killed or driven out of town.
Because of Innsmouth's remote location, and the fact that non-members had been frightened into silence, the Order was able to get away with this for decades.
Aim of the Order
Taking its name from one of the Old Ones, Dagon, it seemed that the long range aim of the Order was to summon the Old Ones from their empty dimension prison.
It remains unknown if the Order was aware of others also making plans to free the Old Ones (such as the Martense family).
How the Order themselves planned to free the Old Ones also remains unknown. However, they would never get the chance to do so.
The end of the Order
In the late 1920's the Inner Circle uncovered the plans the Order. They had dispatched one of their members, Robert Olmstead, to Innsmouth, to confirm their suspicions. When Olmstead discovered just what The Esoteric Order Of Dagon had been planning he reported his findings back to the Circle, who then acted on said findings.
The Circle used its influence in the U.S. Government to organize a raid on Innsmouth. In said raid, many buildings, starting with the Order's headquarters, were blown up. All its members, including the Innsmouth hybrids, were arrested (the Innsmouth hybrids would be sequestered from the rest of humanity for the rest of their lives, for their own protection).
The Deep Ones were dispatched by the U.S. Navy.
Legacy of the Order
Today no trace remains of the Order in Innsmouth. However, records of its legacy remain, as Rex Buckland and Hannah Webster discovered, when they visited Innsmouth in 2015.
It is not known if The Esoteric Order Of Dagon still exists anywhere else in the world.
References
The Shadow Over Innsmouth by H.P. Lovecraft
Rex and Hannah Chronicles Story No. 37: Skeletons In Closets
Rex and Hannah Chronicles Story No. 38: Innsmouth Revisited
Rex and Hannah Chronicles Story No. 39: The Inner Circle