The Last Alliance of Elves and Men was a joint coalition formed in the Second Age in response to Sauron's threat of conquest.
History[]
Sauron had been contending with the Elves for mastery of Middle-earth for over 1200 years. Fearing the establishment of the powerful kingdoms in exile — Arnor and Gondor — by his hated enemies, the Dúnedain, Sauron launched a preemptive attack on Gondor in S.A. 3429.
Isildur left Minas Ithil for the north to meet his father and High King of the Dúnedain Elendil, whilst Anárion, Elendil's younger son, defended Osgiliath against the hosts of Mordor.
In response, Elendil joined with Gil-galad, the Noldor Elves' High King, to repel Sauron's attacks. Durin's Folk joined them as well. Elendil was said to have bound this partnership under an oath, invoking Eru's name, which was rarely spoken of in oaths, and only the King would call upon him in Numenor, and in thousands of years later, would be done again in the Oath of Cirion.
The hosts of Gil-galad and Elendil met at Amon Sul (Weathertop), marching to Imladris (Rivendell), camping for three years and then making plans for war and armor.
Their armies crossed the Misty Mountains, Gil-galad and Isildur crossed the Pass of Imladris and Pass of Caradhras, forcing the Mordor Orcs sent by Sauron, to hide from the size of their force. Their numbers were bolstered by Elves from Lothlorien and Greenwood in the Anduin Vales, under Amdir and Oropher, and Dwarves of Moria.