The Esoteric Order of Dagon has its headquarters in the old Masonic Hall. By Jack's words it is the only building in Innsmouth that does not look like it is about to collapse. It is also the center of Marsh family power over the city. The building was bought by Obed Marsh around 1840 when he founded the Order. The building also has its own prison and the old smuggling tunnels leading out to the harbour. Inside the building there is a magical portal leading out to Devil's Reef. The building is the home of Robert Marsh and it is the place where the leaders of the Esoteric Order of Dagon meet. Jack in the mission "The Esoteric Order of Dagon" must fight the way trough the building and stop the ceremony that prevents the Marines to brake inside.
The Esoteric Order of Dagon is a religious cult that is stationed in Innsmouth. It was founded by Obed Marsh who met the natives of Polynesian islands who worshiped the ancient sea deities known as the Old Ones. This sea gods were known as Father Dagon and Mother Hydra. Worshiping them and bringing them human sacrifices would give anyone the limitless supply of fish and even gold now and then. The natives of this islands were known as Kanakies and they also worrshiped the race known as the Deep Ones. Kanakies were bringing human sacrifices and were mating with this Deep Ones. The ship captain from Innsmouth known as the Obed Marsh traveled the Pacific where he found this natives. Their leader, Walakea, gave Obed the knowledge to summon the Deep Ones and how to bring human sacrifices. Around 1840,Obed and his sailors bought the Old Masonic Hall and founded the Esoteric Order of Dagon. By 1845 Obed, his family and citizens that were around him were the most powerful in Innsmouth. In 1846 the Christian folk of Innsmouth started a rebellion against Obed. The ceremonies and too many missing were the main reason for it. Obed and his Order were locked up in the old jailhouse. Few days later the Deep Ones, angered by the abolishing of the Order, lead their attack on the city. Nearly half of the town was slaughtered that day. This resulted in: Obed becaming dictator of the city, Order becoming the only religion in Innsmouth; the citizens were forced to take the Oaths of Dagon. There were three Oaths. The most horrific was the third one wich forced male or female human to mate with male or female Deep One. Obed died in 1878 and his descendants continued control over town until the U. S. Army launched attack on the city in 1922.