The Dawnguard is a group of Vampire hunters that originate from the province of Skyrim. They are based in Fort Dawnguard, in the region of the Rift, towards the provincial border in the Velothi Mountains. It is found in the Dayspring Canyon of the Velothi Mountains.
The Dawnguard traces its origins in the early to mid Second Era. Fort Dawnguard was once a stronghold owned by the Jarl of Riften. The Jarl's son was an adventurer, which proved to be his demise when he contracted Vampirism. When the Jarl of Riften realized what happened, he was unable to have his son killed, and so he used his money to build Fort Dawnguard as a prison to hold his son. The hired men that guarded the prison would become the early Dawnguard. The Dawnguard was eventually forced to kill the Jarl's son, which led to the group's banishment from the Rift. However, the Dawnguard stuck to their cause of vampire hunting. A silver and gold sword known as the Guardian's Claymore was bestowed on the first leader of the Dawnguard back in the Second Era, and is renowned for its ability to block attacks. The group would start to use Crossbows with Silver bolts. A weapon that would later be used by the Fighters Guild during the Interregnum. The group would eventually dissolve and fall into obscurity. A rumor was that the group had all contracted vampirism and stalked the Rift until they were all defeated.
In 4E 201, the Vigilants of Stendarr had established a chapter in Skyrim, specifically in the region of the Pale. One of their members, Isran had left the group to reform the Dawnguard. Keeper Carcette had mocked Isran's desire to rebuild Fort Dawnguard, and that it was not worth the manpower to repair. Isran believed that the Vigilants were weak, and very unprepared for a real threat. As a Vampire threat had begun to emerge out of Skyrim, the word about the Dawnguard and their stronghold would spread across the province. At one point, the Vigilants of Stendarr were wiped out by the Volkihar Clan, and the remnants of the group sought help from the Dawnguard. The Dawnguard's investigation of the vampiric threat, as well as, the Dimhollow Crypt had led them to the discovery of Serana, a Daughter of Coldharbour. What followed after was a conflict between the Dawnguard Vampire Hunters, and the Volkihar Clan, which would involve the prophecy known as the Tyranny of the Sun. In the end, the prophecy was not fulfilled, and Tamriel was spared from danger. The Dawnguard would continue to operate in Skyrim.