Gondor captures Umbar (933 T.A.) - After the fall of Númenor, Umbar, its greatest colony turned to the worship of Melkor and became allied with Sauron.  As a result, it also became one of Gondor's greatest rivals in southwest Middle Earth.  Their proximity to one another insured there would be conflict.  In 933 Eärnil, the 13th King of Gondor scored a major coup by capturing it in a surprise attack.

 

"Eärnil I repaired the ancient haven of Pelegir, and built a great navy.  He laid siege by land and sea to Umbar, and took it, and it became a great harbour and fortress of the power of Gondor." ~The Return of the King (Appendix A)

 

"933 King Eärnil I takes Umbar, which becomes a fortress of Gondor." ~The Return of the King (Appendix B)