Fall of Minas Ithil
This article describes a concept which is mentioned in J.R.R. Tolkien's works, but was never given a definite name.
After the Downfall of Númenor in 3319, the sons of Elendil brought their ships up the Anduin and together founded the realm of Gondor. While Anárion set up his house in Minas Anor, his brother Isildur established his house in Minas Ithil in a pass in the Ephel Dúath on the border of Mordor.
But Sauron also escaped the Downfall and returned to Mordor. There he built up his strength until he could assault the exiled Númenóreans. In 3429 a great force took Minas Ithil, drove out Isildur, and burnt the White Tree. Isildur escaped with his wife, his sons, and a seedling of the Tree. They traveled to Elendil in the north while Anárion defended Osgiliath and kept Sauron at bay.