Host of the West (Arnor)
The host composed of a vast army from Gondor (actually just a small force compared to the full might of Gondor) that arrived in a massive fleet, which could barely find harborage, even after filling Forlond, Harlond, and the Grey Havens. Alongside the Gondorians were allied Northmen of Rhovanion with their horses from the Vales of Anduin. Earnur led the cavalry during the Battle.
Círdan, Lord of Lindon, summoned all who would fight from the Elves of Lindon, as well as the remnants of the Dúnedain of the North. Among the forces of former Arthedain were some Hobbits from the Shire.
The main body of the Allies' horsemen, was to pass around the hills to surprise Fornost from the north.
In T.A. 1973 Arthedain was in danger and King Eärnil II sent his son Prince Earnur and a massive fleet to their aid. After Arnor fell to Angmar, Prince Eärnur and his fleet reached belatedly Lindon to the aid of Arthedain.
Although it was too late, the fleet and the host it brought, seemed so massive, that there was much joy and wonder among Elves and Men. The allied host, led by Cirdan and Earnur, marched east across the river Lune to Fornost to challenge the Witch-king, and crushed him at the Battle of Fornost (T.A. 1975).