Born the year 2776 TA, in the Iron Hills, son of Úlfur a guard officer of Grór.

Beginnings in the military life 
Of strong character and stout physical contexture from an early age attempts to join the army, even before they are old enough for a dwarf to bear arms, which is why his desire was severely opposed by his father, running away from his home in Baruk-khizdin for realize their dreams of being a soldier. Was initiated in the military career at a very young age (20 years old in 2796 TA) joining the dwarven forces during the War of the Dwarves and Orcs, trained under strict discipline, Bjornen reinforced the tempering of his unwavering character, becoming a strong upward military. He participated in the “The Second Sacking of Gundabad” (2798 TA) battle in which he loses an eye, which does not prevent him to march one year after with the seven clans army at the gates of Moria where the war ended at the Battle of Azanulbizar. At the end of this, the most terrible of the battles, he must burn the body of his father who dies before he was able to make peace with him. 
Returns to the Iron Hills where he completed his formal training as part of the army of Dain Ironfoot, winning the title of lieutenant for his services in battle. In 2941 TA march with Dain Ironfoot with an army of 500 dwarfs between veterans and the vanguard towards the Lonely Mountain answering the call of the relative of Dain and King in exile Thorin II Oakenshield, Bjornen is remembered in this episode for been sent by Dain with other officers to parley with the King of the Elves and the leader of the refugees from Esgaroth who besieged the mountain. When these consult him Bjornen answers:

"We are hastening to our kinsmen in the Mountain, since we learn that the kingdom of old is renewed. But who are you that sit in the plain as foes before defend walls?"

The events that took place after came to be known by many as "The Battle of the Five Armies". 
 

Reconstruction of Erebor and the Great Road of the Dwarves

Thanks to the overwhelming victory of the armies of Dain Ironfoot, Thranduil and Bard is that the population of Orcs and goblins decreases significantly along with their activities in the Misty Mountains and the Wilderland. During the next two years Bjornen stays with the new King Under the Mountain Dain II Ironfoot until 2943, year in which leading a large company of dwarven soldiers with the rank of Zabad, travels east with the mission of protect the workers in charge of rebuilding the Great Road of the Dwarves, setting its base near the ruins of what was once the dwarven city of Usjarûrzahar remaining nearly 50 years in the eastern regions, facing continuously bands of easterling bandits. The year 2993 T.A. returns back to the Iron Hills where he served under the command of Thorin III Stonehelm Dain's Son, Nain's son.

Trip to the Blue Mountains
Alerted by the increased activity of the easterling kingdoms, former allies of the Dark Lord Sauron, added it to arrival of messengers of Mordor to  the Lonely Mountain, Dain II Ironfoot convenes in Erebor  to his generals. As part of the measures taken by the king is to maintain a expeditious route for supplies between Thorin's Halls and Eriador and the mansions of the Dwarves in the east. leaves Baruk-khizdin at the end of 3018 T.A.