§ Of the Fifth Battle: Nirnaeth Arnoediad The Silmarillion

Then the hearts of the Noldor grew hot, and their captains wished to assail their foes upon the plain; but Húrin spoke against it, and bade them beware of the guile of Morgoth, whose strength was always greater than it seemed, and his purpose other than he revealed. And though the signal of the approach of Maedhros came not, and the host grew impatient, Húrin urged them still to await it, and to let the Orcs break themselves in assault upon the hills.