Therefore if any of his captives escaped in truth, and returned to their own people, they had little welcome, and wandered alone outlawed and desperate.'

But ever the Noldor feared most the treachery of those of their own kin, who had been thralls in Angband for Morgoth used some of these for his evil purposes, and feigning to give them liberty sent them abroad, but their wills were chained to his, and they strayed only to come back to him again. And Morgoth sent out his spies, and they were clad in false forms and deceit was in their speech they made lying promises of reward, and with cunning words sought to arouse fear and jealousy among the peoples. 'Many of the Noldor and the Sindar they took captive and led to Angband, and made them thralls, forcing them to use their skill and their knowledge in the service of Morgoth. The aftermath of the Dagor Bragollach (Battle of Sudden Flame) I 455 meant capture of large numbers of elves:

The Silmarillion, Quenta Silmarillion, Ch 13, Of the Return of the Noldor Thus Morgoth learned much of all that had befallen since the rebellion of Fëanor, and he rejoiced, seeing therein the seed of many dissensions among his foes.' And desiring above all to sow fear and disunion among the Eldar, he commanded the Orcs to take alive any of them that they could and bring them bound to Angband and some he so daunted by the terror of his eyes that they needed no chains more, but walked ever in fear of him, doing his will wherever they might be. '.in his rear and to the north Morgoth had no foes, and by that way his spies at times went out, and came by devious routes into Beleriand. It lasted until Morgoth's downfall in the War of Wrath. Summary: a strategy that began after the Dagor Aglareb (Glorious Battle), while Morgoth was beset by the Siege of Angband.

Skills angband