§ Of the Return of the Noldor The Silmarillion

At Mereth Aderthad many counsels were taken in good will, and oaths were sworn of league and friendship; and it is told that at this feast the tongue of the Grey-elves was most spoken even by the Noldor, for they learned swiftly the speech of Beleriand, whereas the Sindar were slow to master the tongue of Valinor. The hearts of the Noldor were high and full of hope, and to many among them it seemed that the words of Fëanor had been justified, bidding them seek freedom and fair kingdoms in Middle-earth; and indeed there followed after long years of peace, while their swords fenced Beleriand from the ruin of Morgoth, and his power was shut behind his gates. In those days there was joy beneath the new Sun and Moon, and all the land was glad; but still the Shadow brooded in the north.