Rattletail was a village located somewhere in Baja.
It was founded by New California Republic settlers who had moved into Baja, sometime between 2256 and 2261. According to Hanlon the village was nothing more than six shacks built around a well. Hanlon was sent with six other NCR Rangers to investigate reports of raider attacks on the settlement. It took the rangers about a week to get there, with one dying from a night stalker attack and another nearly dying from dehydration.
When the rangers arrived, they discovered 5 men with hunting rifles defending the village, and over 24 dead bodies behind a dune nearby. While investigating the bodies, Hanlon discovered that the people the villagers had killed were not heavily armed raiders but simply locals trying to access the water in the town's well.
Seeing that the settlers of Rattletail seemed resolved to defend their well to the death, Hanlon created a story about a group of 100 raiders poised to attack the village in order to get them to leave. He also said that the raiders had already killed 10 of his Rangers. This convinced the villagers to return back to NCR territory. The former residents of Rattletail resettled in Anza-Borrego, in pre-War Southern California, and were having success there raising bighorners.
Rattletail is only mentioned in Fallout: New Vegas.