Brotherhood-Enclave War

The was a military conflict in 2277 between the Brotherhood of Steel and The Enclave.

Prelude
When the Brotherhood arrived in the Columbia Commonwealth area in 2257, they did not yet know that the Enclave, who were defeated by the California chapter of the Brotherhood and the New California Republic sixteen years ago, had fled to the Columbia Commonwealth. Under the leadership of Owyn Lyons the Brotherhood began combating the local Super Mutants, unaware of the rebuilding Enclave.

War
In 2257, the Enclave began to spew out a propaganda campaign against the Brotherhood. The Enclave, now under the leadership of president John Henry Eden, plotted in secret at Raven Rock. For twenty years, there was no interaction between the two, leading many to suspect the Enclave radio broadcasts were on an old loop. However, in 2277, Colonel Augustus Autumn led an attack on the Jefferson Memorial, and took over Project Purity, as part of their plan to "purify" the wasteland.

The Brotherhood Outcasts were also attacked by the Enclave on patrol or at their outposts. Helpless against them, they stayed at their base instead of going out and fighting against them.

After the Jefferson Incident, the Enclave began a conquest of the Columbia Commonwealth. They took over the Jefferson Memorial, satellite relay station, Adams Air Force Base, SatCom Array NW-07c, Old Olney, and Raven Rock. They also established small camps & outposts around the wastes. They even tried to annex Vault 101 as a vantage point.

The Brotherhood began to try and get evidence that Project Purity could restart so they could reclaim the Memorial. The Enclave got wind of this, and kidnapped the Lone Wanderer in Vault 87, confiscating the G.E.C.K.. The Lone Wanderer woke up and cleared out the staff of Raven Rock, he then spoke to president Eden (revealed to be a ZAX computer),and was given a Modified FEV vial. He then destroyed raven rock while the surviving Enclave staff fled to Adams air force base.

After the Brotherhood received the G.E.C.K. and the vial, they were plotting a reclamation of the Memorial. Lyons permitted the battle, and gave them the support of Liberty Prime. After storming the Memorial, Autumn was killed in the battle, and the purifier was started, and the wasteland had pure water. Two weeks later, the Brotherhood dispensed the water throughout the wasteland. The Enclave, after it's defeat, made a last stand at Adams Air Force Base. When the Brotherhood invaded their satellite station, the base was destroyed, but Liberty Prime was eliminated, a major blow for the Brotherhood. After creating the Tesla cannon, they launched a final attack on Adams AFB. The Enclave stood a last defense, but were defeated by the Brotherhood. As a last resort, Whitley, a scientist, launched his prototype Eyebot, ED-E, to go to Navarro and complete a mission. The mission is unknown.

Looking at the launch terminal, it appears they were planning to eradicate the settlements of Megaton and Rivet City. They also had Project Purity, and the Citadel as targets. You can target the Citadel if you want and completely destroy the Brotherhood, or target Adams and conquer the Enclave. Neither option has been confirmed as canon.

Outcome
Despite the destruction of Adams Air Force Base remnants of the Enclave will continue to roam the wasteland.