Oslaf

Background
Oslaf is a soldier that accompanies Beowulf on his venture to defeat Grendel. The warrior is a veteran from the Frisian Battle of Finnsburg, a conflict between Hnaef's company and the Lord of Finnsburg's retinue. He and his companion Guthlaf can be attributed to the continuation of the conflict after convincing Hengest, the right hand man of the late Hnaef, to take revenge on Finn while he was still in Frisia.

Finnsburg Fragment
The Finnsburg Fragment is an old English poetry collection that depicts the warring between the Hoclings and the Finnsburg Frisians. In the Fragment, Hnaef and his retinue of 60 men-at-arms were attacked after they were invited to the halls of Finn. Hnaef was slain, and his second-in-command Hengest took command of the remaining soldiers. They remained besieged in the halls for 5 days with no fatalities. The fragment has much of it's context lost to time, but the revenge begins again in the early lines of Beowulf.

Beowulf (The Continuation War)
In Beowulf, it begins to describe the short peace between the Hoclings and the Frisians. The thanes of the Hoclings and Finns agree to a truce, but shortly after the companions Guthlaf and Oslaf return to the Danes and convince Hengest to exact revenge among the Finn and his thanes. All of the Frisians were slaughtered by the Danes, and the final battle ended the fued between the parties.

Finnsburg Fragment
In the siege of Hnaef's retinue, Oslaf was tasked with the forward defense of one of their flanks. Not much description is given of the battles, but from the lack of any fatalities of Hneaf's men, the pair can be assumed to be victorious. Even in a foreign land, besieged for 5 days, he held against the Frisians well, and maintained the respect of his brothers-in-arms. Unfortunately, he was no Beowulf. Oslaf remained a minor character even through Beowulf, as his strength was that of a great soldier, not a mythical warrior.

Beowulf
After the first Battle of Finnsburg, Oslaf returned to his brethren in Denmark. He told the stories of Frisia, and built the morale of his companions with his valor and speeches. In addition to this, he managed to survive the Second Battle of Finnsburg, slaughtering the thanes of Finn alongside what remained of his party.