The NCR-Great Khan War is an ongoing conflict between the New California Republic Army and the Great Khans. The roots of the conflict date back to when the NCR was nothing more than the settlement of Shady Sands and the Khans weren't yet called the Great Khans. Full scale conflict, however, would start when the NCR would attempt to annex tribals, including the Great Khans which would have the war culminate in the Bitter Springs Massacre.
When the residents of Vault 15 left the vault, four distinct groups were founded, including the Khans and the settlers of Shady Sands. The Death Hand, founder of the Khans, began raiding the small settlement of Shady Sands. The raids remained minor until Garl Death-Hand, The Death Hand's son, kidnapped Tandi, the daughter of Aradesh, who would later become the first president of the NCR. Aradesh then tasked the Vault Dweller to retrieve his daughter from the Khans. The resulting battle caused the deaths of all the Khans except one, named Darion.
Darion became paranoid and obsessed with revenge against the Vault Dweller and Tandi, who later became the second president of the NCR. He founded the New Khans with the sole purpose of taking revenge on the NCR. In an ironic twist of fate, Darion, now an old man, was killed in 2241 by the Chosen One, the grandchild of the Vault Dweller who had killed his companions 80 years earlier.
Great Khans and Rising Conflict
The remnants New Khans would reform as the Great Khans, led by Papa Khan. He and The Great Khans left California for the Mojave Wasteland. There they became powerful, and were known as the "Flails of God." The Three Families and Robert House drove them out of outer Vegas, weakening their hold in the area. As supplies and fresh water began to dwindle, overcrowding was becoming more and more apparent. The New California Republic sent its elite Rangers and scouts into the Mojave Wasteland in search of fertile lands and resources to help expand their borders for their ever growing population.
Push to the Mojave
After entering the Mojave, NCR president Wendell Peterson aimed to gain more land in the Mojave so as to gain a foothold over other factions, most prominently the Brotherhood of Steel. In order to fulfill this task, Aaron Kimball would begin a campaign to secure the Mojave and annex the local tribals, of which the Great Khans were the most prominent. Kimball's campaign would be an utter failure, and the Great Khans would begin to attack the NCR settlements. The NCR would retaliate by attacking the Great Khans. Skirmishes would continue, despite the fact that the Great Khans were weakened both by Robert House and the NCR's firepower. The Great Khans would also have the Fiends aid them in the conflict after they began supplying Chems to the raiders.
The NCR would continue to pursue it's goals in the Mojave Wasteland by attempting to eradicate the Great Khans. The NCR believed to have found the main headquarters of the Great Khans at a location known as Bitter Springs. They failed to realize that Papa Khan had led the main Khan fighting force out of Bitter Springs before they had arrived. In 2278 the NCR sent the 1st Recon unit under the command of Major Gilles to Bitter Springs in the hopes of decimating the Khans fighting force. Commanded to fire until they ran out ammo, the 1st Recon unit would inadvertently slaughter the women, children and elderly citizens of the Great Khans. Referred to as the Bitter Springs Massacre, the incident outraged the Great Khans and was heavily criticized by both proponents and opponents of the NCR as a major tactical mistake.
Decimated at Bitter Springs, the remaining Great Khans and their leader, Papa Khan, would move into Red Rock Canyon where they would have a strategical advantage over the NCR. The NCR would establish Ranger Station Foxtrot to keep an eye on the Great Khans and occasionally send a scout, but actual conflict was rare.
The Great Khans would continue to be hostile to the NCR, despite a stalemate and ceasefire having been reached between the two. The Great Khans would strengthen their relations with the Fiends, who engaged in skirmishes with the NCR, attacking trade routes and settlements.