While Beren was still young, the Battle of Dagor Bragollach broke out, leading to Dorthonion's downfall. Later, the young Beren, his father and the other twelve tribesmen who did not want to abandon their homeland lived in Tarn Aeluin, a highland in Dorthonion. They escaped from the demons of Angband many times. Morgoth sent out an army of orcs to hunt them down. After everyone's hiding place was discovered by Sauron through a trick, and all his companions, including Barahan, were killed, Beren took revenge alone. His reputation grew so great that Beren's head was worth as much as the head of Fingon, the High King of the Noldor. After defeating the Orc captain, Beren regained the Ring of Barahir that his father was wearing when he died. This was given to Barahir by Finrod Felagund in the "War of Sudden Fire" to commemorate the two of them. A token of the everlasting friendship between them. Finrod Felagund vowed that if anyone brought Barahir's ring for help, he would answer them. Dorthonion had been completely destroyed by the werewolves sent by Sauron, and Beren had to leave his homeland. After a terrifying journey and an incredible passage through the Ring of Melian, he entered Doriath where he met Elu Thingol and Melian's daughter Luthien. , the two fell in love.
Elu Thingol arrogantly refused to let the two get married. Elu Thingol said that he would only allow the two to get married unless Beren could hand over one Silmaril, and three Silmarils. All fell upon Morgoth. Elu Thingol thought this was impossible. Beren and Lúthien ventured (to face Sauron) to Angband with the assistance of Finrod Felagund and the divine dog Huan. Lúthien chanted a spell to put Morgoth to sleep, and Beren took one of the Silmarils. When he tried to take another Silmarillion from Morgoth's iron crown, his dagger Angrest (Angrist) broke and struck Morgoth. They wanted to escape, but the giant wolf Carcharoth raised by Morgoth attacked them. Beren took out the Silmarillion, hoping that the light of the Silmarillion would drive away Carcharoth. Unexpectedly, Carcharoth was captured by the treasure. The Diamond was bewildered by the light and swallowed Beren's hand along with the Silmarils, lost his mind and ran to Doriath. Lúthien and the unconscious Beren were rescued by a giant eagle. They returned to Doriath. Beren claimed that he had taken the Silmarillion and showed his severed arm to Elu Thingol. Elu Thingol began to sympathize with Beren, and Beren participated in the hunt for Kaheros and regained the Silmarillion, but Beren also suffered a fatal blow.
When Lúthien learned of Beren's death, she was so heartbroken that she also died of illness. Lúthien's spirit came to the halls of Mandos and sang the most beautiful song ever sung, and even Mandos was moved. Beren and Lúthien were reborn, both as humans. The two left Arda and returned to Middle-earth, where they lived on the island of Tol Galen in the middle of the Adurant in Osirion. Beren never interfered in other affairs except when he intercepted a group of dwarves who had stolen Nauglamír, the necklace with the Silmaril.
The two gave birth to a child named Dior, who is the heir of Elu Thingol. He has the blood of humans, elves and Maiar. Dio's descendants continued the lineage of Beren and Lúthien.