After the catastrophe of the Fifth Battle, the Nírnaeth Arnoediad, the boy Túrin is sent to Doriath for protection from Morgoth's special enmity for the House of Húrin. Beleg becomes the mentor, steadfast friend and brother-in-arms of Túrin Turambar. The two fight together in defending the north marches of Doriath from the Orcs of Morgoth. When Túrin is accused of murder, Beleg searches out and produces at the last moment a witness who can testify to extenuating circumstances. When Túrin pridefully leaves Doriath after the affair, Beleg receives permission from Thingol to follow him into exile and is granted the sword Anglachel to help in this endeavour. Beleg long seeks Túrin. At Amon Rûdh he is captured and tortured by Túrin's men, until Túrin returns and releases him. Although Beleg beseeches Túrin to return to Doriath, where he has been pardoned and would be welcomed, Túrin still pridefully refuses and Beleg loyally chooses to stay with Túrin. Together, with Túrin wearing the Dragon-helm of Dor-lómin, they lead a band of men against the invaders of Morgoth. The land where the "Two Captains" dwell becomes known as the Land of Helm and Bow, but the small realm was destroyed two years later.
When Túrin is captured by Morgoth in a treacherous ambush, Beleg is grievously wounded. Yet with the strength of a great Elven warrior and his extraordinary healing skills, he recovers swiftly and tracks the Orcs. In the deadly land of Taur-nu-Fuin Beleg meets the elf Gwindor, recently escaped from Morgoth's thraldom, and together they rescue Túrin, with Beleg performing an heroic feat ofbowmanship, slaying numerous wolf sentinels in the dark. After they carry Túrin from the Orc-camp, while removing Túrin's bonds, Beleg accidentally cut Túrin with his sword. Túrin awakes and does not recognize Beleg in the darkness, mistaking the shape over him with a blade as an Orc. In a sudden rage of self-defence, he wrests the sword from Beleg and kills him. When he recognizes the truth of his friend's loyalty and bravery and his own fatal mistake, Túrin is so overcome with grief that he walks in a daze for weeks, being led out of danger by Gwindor. After returning to himself, Túrin takes Beleg's sword Anglachel, renaming it Gurthang ("Iron of Death"), and wields it in further battles against Morgoth's forces for the rest of his life. Years later, Túrin himself dies upon the sword Gurthang when his tragic life becomes too hard to bear, and the sword is thus avenged for the death of Beleg.
Out of curiousity, if Túrin is the one portrayed on the left, why is his sword not black?