Sauron attacks Gondor
Event Type: Military/Strategic
Age: Akallabêth/Last Alliance
Sauron was indeed caught in the wreck of Númenor...; but he fled back to Middle-earth.... He was unable ever again to assume a form that seemed fair to men, but became black and hideous, and his power thereafter was through terror alone. He re-entered Mordor, and hid there for a time in silence. But his anger was great when he learned that Elendil whom be most hated, had escaped him, and was now ordering a realm upon his borders.
Therefore, after a time he made war upon the Exiles, before they should take root.
The Return of the King, LoTR Appendix A, Annals of the Kings and Rulers: Númenor
Sauron... came in secret... to his ancient kingdom of Mordor beyond the Ephel Dúath..., and that country marched with Gondor upon the east. There... was a fiery mountain in that land that the Elves named Orodruin....
Now Sauron prepared war against the Eldar and the Men of Westernesse, and the fires of the Mountain were wakened again. Wherefore seeing the smoke of Orodruin from afar, and perceiving that Sauron had returned, the Númenóreans named that mountain anew Amon Amarth, which is Mount Doom. And Sauron gathered to him great strength of his servants out of the east and the south; and among them were not a few of the high race of Númenor. For in the days of the sojourn of Sauron in that land the hearts of well nigh all its people had been turned towards darkness. Therefore many of those who sailed east in that time... were already bent to his will, and they served him still gladly in Middle-earth. But because of the power of Gil-galad these renegades, lords both mighty and evil, for the most part took up their abodes in the southlands far away....
When therefore Sauron saw his time he came with great force against the new realm of Gondor....
The Silmarillion, Of the Rings of Power and the Third Age
Elena Tiriel 3Dec07