After the Great War, survivors and vault dwellers settled the city of Portland, using its resources to create Bridge-Town. The town was sacked over and over again from raider gangs and residents from Vault 38. The town quickly fell into disarray soon after formation, getting picked up again by the Oregon Republic.
After the formation of the Oregon Republic in Oregon City, scouts were sent north to investigate the Pre-War city of Portland. They returned with news that residents there called it Bridge-Town, and that there was an influx of raiders killing and stealing. The army moved north, entering the ruins of Portland to engage with the raiders. This became known as the First Battle for Portland, which saw the Oregon Army defeated by various raider gangs. The army regrouped and resupplied just outside the city in the ruins of Oregon City (Pre-War Oregon City). Under new leadership, the army engaged the raiders a second time in the Second Battle for Portland, crushing the raiders and moving further in towards the city. In Bridge-Town, they encountered Vault 38, whose residents attacked at first sight, resulting in the destruction of the vault and its residents in the Battle of 38.