The Enclave

Members of the Enclave both embraced the idea of a nuclear war and knew that the common man could not survive it. They believed that as long as the "important people" of the United States survived, they could regroup quickly and wipe out Communism once and for all. Though not technically part of the Enclave, many powerful corporations benefited from the Enclave's actions, and their research facilities were protected during the nuclear firestorm of 2077.

In 2073, as the global race to exploit the handful of remaining fossil-fuel resources reached its fevered peak, the United States managed to stake a claim on the world's last known supply of crude oil, buried thousands of feet beneath the Pacific Ocean. Poseidon Energy, a major American energy company, was contracted to build an oil rig and extract the oil. Before long, the oil ran dry and the oil rig was abandoned by Poseidon.

In 2077, with total nuclear war imminent, the President of the United States and a number of other American government officials left their posts in Washington, D.C. to take refuge in a number of secret and isolated locations around the United States. Among them was the Poseidon Oil Rig off the coast of California. Here, the President himself set up a secret base from which the United States could continue to exist and wage war on China, with the eventual goal of retaking the continental United States from its post-atomic state. From 2077 on, the remnant of the American government surviving on this oil rig started to openly call itself the Enclave. In dialogue with Arcade Gannon, in Fallout: New Vegas, it is revealed that after the Fall of the Oil Rig, the NCR eventually overran Navarro. This caused all Enclave forces in the West to scatter or head to the east. There, the Enclave set up bases in Raven Rock and Adams Air Force Base, unfortunately these bases are both destroyed by the Brotherhood of Steel and unless there are other bases (Chicago is mentioned in the audio logs during ED-E My Love) that are still operating, the Enclave is effectively crippled.

The Enclave mostly continued the pre-War American government, making alterations to fit their smaller size and increase the fluidity of operations. Some new departments that were established after the Great War included the Atomic Energy Commission and the Chemical Corps.