Cair Andros

About forty miles upstream of Osgiliath the Anduin divided around a long island whose northern end rose in a sharp prow against the current, throwing up white foam; the name means the ship of long foam. Because an enemy who crossed here could reach Anórien and come at Minas Tirith from the north, cutting the road to Rohan, the Men of Gondor had fortified the island with walls and a garrison and held it as one of their two northern crossings, the other being Osgiliath itself. Faramir reckoned it, with Osgiliath and the Causeway Forts, among the places that the Steward could not afford to lose.

In March 3019 Sauron's northern force crossed the river above Cair Andros, took the island on March 10 to 11, and entered Anórien to block the Rohirrim; the beacons had already been lit. The Rohirrim avoided this force by taking the Drúedain's road through the Drúadan Forest, and after the Battle of the Pelennor Fields Elfhelm and the Riders drove the invaders out of Anórien. When the Host of the West marched from Minas Tirith on March 18 it passed the Crossroads and sent a detachment to retake Cair Andros; on March 21, near the island, Aragorn allowed the men who could not face the Morannon to go there instead and hold it against any enemy. In the Fourth Age the island was once more a peaceful post of the Reunited Kingdom.

Cair Andros lay in the Anduin between Anórien on the west and northern Ithilien on the east, north of Osgiliath and south of the marshy Mouths of Entwash. The road north from the Crossroads ran along the eastern bank past it towards the Morannon.