§ Of the Sindar The Silmarillion

But the victory of the Elves was dear-bought For those of Ossiriand were light-armed, and no match for the Orcs, who were shod with iron and iron-shielded and bore great spears with broad blades; and Denethor was cut off and surrounded upon the hill of Amon Ereb. There he fell and all his nearest kin about him, before the host of Thingol could come to his aid. Bitterly though his fall was avenged, when Thingol came upon the rear of the Orcs and slew them in heaps, his people lamented him ever after and took no king again. After the battle some returned to Ossiriand, and their tidings filled the remnant of their people with great fear, so that thereafter they came never forth in open war, but kept themselves by wariness and secrecy; and they were called the Laiquendi, the Green-elves, because of their raiment of the colour of leaves. But many went north and entered the guarded realm of Thingol, and were merged with his people.