As a son-in-law of Hador, he fostered Hareth's sons Huor and Húrin in Brethil, as was the custom of the Edain in those times. With them he joined the ambush of Orcs that came from the Pass of Sirion soon after the Dagor Bragollach, and the forces of his father Halmir utterly defeated the enemies.
Haldir was slain with most of his men in the rearguard of Fingon's retreating army. To Brethil only three men returned, and learning the news of the fall of her husband, Glóredhel grieved and died. The Folk of Haleth was ruled afterwards by their son Handir.