Three Year's Thrall by Anu

"Now when Tuor was sixteen years old the Elves were minded to leave the caves of Androth where they dwelt, and to make their way secretly to the Havens of Sirion in the distant south; but they were assailed by Orcs and Easterlings before they made good their escape, and Tuor was taken captive and enslaved by Lorgan, chief of the Easterlings of Hithlum. For three years he endured that thralldom, but at the end of that time he escaped; and returning to the caves of Androth he dwelt there alone, and did such great hurt to the Easterlings that Lorgan set a price upon his head. But when Tuor had lived thus in solitude as an outlaw for four years, Ulmo set it in his heart to depart from the land of his fathers, for he had chosen Tuor as the instrument of his designs; and leaving once more the caves of Androth he went westwards across Dor-lomin, and found Annon-in-Gelydh, the Gate of the Noldor, which the people of Turgon built when they dwelt in Nevrast long years before. Thence a dark tunnel led beneath the mountains, and issued into Cirith Ninniach, the Rainbow Cleft, through which a turbulent water ran towards the western sea. Thus it was that Tuor's flight from Hithlum was marked by neither Man nor Orc, and no knowledge of it came to the ears of Morgoth."

-The Silmarillion, Chapter 23 'Of Tuor and the Fall of Gondolin', page 238.