The Brotherhood of Steel is one of the most iconic factions out of the Fallout franchise, as its Power Armor is often the most sought-out gear in the game and is part of the game posters and box art. The Brotherhood has been in every Fallout title to date.
However, not every part of the Brotherhood of Steel sees eye to eye. They have sub-factions with different goals and ideas, but the most significant split within their organization is between the eastern and western Brotherhood. The west Brotherhood wishes to focus on preserving technology and keeping it out of irresponsible hands, while the east Brotherhood focuses more on helping wastelanders in need.
Before The Split
The Brotherhood of Steel was founded by Roger Maxson, a solider that survived the Great War and witnessed monstrous experiments with FEV at West Tek. Due to his experiences, Maxon founded the Brotherhood of Steel on the basis that the United States failed in protecting its people. His conclusion was that the Brotherhood of Steel will protect what the United States could not, which is to protect people from themselves and their own ignorance.
In its first years, the Brotherhood of Steel focused on helping Great War survivors. However, this changed when Maxson realized human knowledge could disappear. Instead of focusing on people, the Brotherhood then instead focused on preserving technology, books, weapons, and more.
During the time of Roger Maxson, a split in the Brotherhood started to form. Most of the Brotherhood of Steel wanted to be isolated while Roger Maxson did not. When Roger Maxson died, the Brotherhood became isolated which meant that it did not recruit outsiders. At this time, the Brotherhood was on the western side of the United States. It set its eyes on expanding east, which was the next big step in its regional split.
Rise Of The Eastern Brotherhood
The Brotherhood of Steel, though isolated, wanted to expand to the east to collect knowledge. The ruling council decided to give this mission to a Paladin named Owyn Lyons. Upon his mission, Lyons discovered a huge piece of technology that promoted him to an Elder. He discovered Liberty Prime, a massive robot made by the U.S. army. However, Lyons decided that his mission was far from done in the Capital Wasteland. He sent word to the western council that he planned on staying to help those in need, rejecting the Brotherhood's ongoing isolationism.
This made the western Brotherhood cut off Lyons and his team. Most of those under Lyon's command remained loyal to Lyons while some left. Lyons was an older man and eventually passed away, so his daughter led the eastern Brotherhood for a while before she passed away in battle. The next big leader, a descendant of Maxson, grew up with the eastern Brotherhood. However, when he became leader, he began to reestablish their relationship with the west and its mission.
The Big Differences Between The East And West
The founder of the Brotherhood of Steel, Roger Maxson, wanted the organization to both help people and also preserve technology. His idea came through, but never in a united front. The east coast Brotherhood dedicated itself to helping people while the west side concerned itself on just knowledge collection.The western Brotherhood became outmatched by other factions such as the NCR, which made them double down in its isolation and technology hoarding.
While the west became reactionary to competition, the eastern faction was different. Lyons made the Brotherhood a place of aid, charity, and open dialogue with Wastelanders. His kindness cost the faction territory and its relationship with the west. While the west began to care only for the advancement of the faction, the east cared about the advancement of all humanity. Not only were its members active in politics, but they focused on killing super mutants, feral ghouls, and raiders.
When Lyons passed away and Maxson rose to the faction leader in Fallout 4, the eastern Brotherhood quit being charitable but still set itself apart from the west. While the west hoarded technology to survive against the competition of the NCR, Mr. House, and Legion, Maxson's eastern Brotherhood sought to control technology to protect mankind. He even kept some of Lyon's ideas, such as improving technology instead of just hoarding it. The west gained a sort of religious fervor that the east did not. In the west, The Codex is treated like a sacred text rather than just laws, and the founder, Roger Maxson was deified. His descendant who took control of the eastern Brotherhood rejected this idea of being divine.
Fallout 5 is still in early development.