Tryggvason's name is cloaked in an air of great adventure. Although there
is little biographical material to be found about him, there are many tales
of his exploits as Viking, athlete and army leader.
Olav was relatively young when he set out on his first Viking raid. He took part in a long series of battles in the Baltic countries, the Netherlands, England, Scotland and Ireland. The first reliable information about him as the leader of a large and powerful fleet comes from England in 991, where the chronicles mention Olav collecting tribute ("danegeld") from King Ethelred II. Three years later he returned to England on a new raid, this time together with the Danish king, Svend Tveskæg (Forkbeard). Olav subsequently converted to the Christian faith and was baptised in England in 995.
His participation in all these Viking raids had brought Olav Tryggvason great wealth and a skilled army. He now wished to use these assets to claim Norway. Olav set sail for Trøndelag, in mid-Norway, where there was an uprising against Earl Håkon. Following Håkon's murder by the slave Kark, Olav was appointed king at the Øreting assembly. He also won his ancestral territory, Viken, the Oslo region.
Olav Tryggvason was determined to introduce the Christian faith in his territory. In Viken this undertaking was successful; Christianity was accepted and formally adopted by the "ting", or legislative assembly. However, in Trøndelag and Hålogaland further north, his mission met with serious opposition.
On a return voyage from Vendland (Pommerania), Olav was challenged by a superior fleet that included the Danish fleet, the ships of the Swedish king, and those of Earl Håkon's sons Svein and Eirik. Olav Tryggvason fell in the ensuing battle, which took place at Svolder near Öresund in southern Sweden. After his death, the Danish king and the Swedish king divided Norway between them.