Ar-Pharazôn

So great was the might and splendor of the Numenoreans that Sauron's own servants deserted him, and Sauron humbled himself, doing homage and craving pardon.

Then Ar-Pharazôn, in the folly of his pride, carried him back as a prisoner to Numenor.

It was not long before he had bewitched the king and was master of his council.

And soon he had turned the hearts of all the Numenoreans, except the remnant of the faithful, back towards the darkness.

At length, Arferazon listened to this counsel, for he felt the waning of his days and was besotted by the fear of death.

He prepared then the greatest armament that the world had seen, and when all was ready, he sounded his trumpets and set sail, and he broke the ban of the Valar, going up with war to wrest everlasting life from the lords of the west.

But when Ar-Pharazôn set foot upon the shores of Amon the Blessed, the Valar laid down their guardianship and called upon the One, and the world was changed.

Numenor was thrown down and swallowed in the sea, and the undying lands were removed forever from the circles of the world.

And it's not unlikely that at least some of the three Numenoreans Sauron gave rings of power to were kingsmen located in or near Umbar.

Eventually, in the year 3261, threatened by Sauron's growing power, Ar-Pharazon, the last king of Numenor, landed a massive army at Umbar and marched towards Mordor to confront him.

Sauron, seeing his army was no match for Ar-Pharazôn, he surrendered himself, and then he goes to Númenor and corrupts it and brings about its destruction.

But afterwards, Sauron returned to Mordor and once again gathered his armies, and we read this in the Silmarillion.