Harald was born as a son of Sigurd Syr, a petty king in Norway, and Asta Gudbrandsdatter. His half-brother Olaf would become King Olaf II of Norway and later be canonized as a saint.

Young Harald received training in combat, seamanship, and the traditional Viking arts. He also learned skaldic poetry, composing verses that would later chronicle his adventures.

At just fifteen, Harald fought alongside his half-brother King Olaf II against Norwegian nobles allied with Danish King Cnut. Olaf was killed and Harald was wounded, beginning his years of exile.

After recovering from his wounds, Harald fled east to the court of Grand Prince Yaroslav the Wise in Kiev. He served as a military commander and formed a lasting bond with the Rus elite.

Harald traveled to Constantinople and joined the elite Varangian Guard serving the Byzantine Emperor. His tall stature and fighting prowess quickly made him a notable warrior.

Harald led Byzantine forces in campaigns across the Mediterranean, fighting in Sicily against the Arabs and in Bulgaria against rebels. He earned fame and accumulated vast wealth through plunder.

Harald rose to become the leader of the Varangian Guard, the most prestigious position available to a foreigner in the Byzantine military. He allegedly blinded Emperor Michael V during a palace coup.

After falling out of favor with the new Byzantine rulers, Harald escaped Constantinople with his accumulated wealth. He sailed through the Black Sea back to Kievan Rus.

Harald married Elisiv, daughter of Yaroslav the Wise, whom he had courted for years. He wrote love poems to her during his time in Constantinople, demonstrating his romantic and poetic nature.

Harald returned to Scandinavia with his vast Byzantine wealth to challenge his nephew Magnus I for the Norwegian throne. He initially formed an alliance with Sweyn Estridsson of Denmark.

After Magnus I died, Harald became the sole king of Norway. He earned the nickname Hardrada meaning Hard Ruler for his harsh methods of consolidating power against rebellious nobles.

Harald established Oslo as a market town and trading center. Though the exact date is debated, Oslo grew to become the capital of Norway, one of his lasting legacies.

In one of the largest naval battles in Scandinavian history, Harald defeated Danish King Sweyn II. Though he won the battle, he failed to capture Sweyn, and the war continued.

After years of inconclusive warfare, Harald finally made peace with Sweyn II, recognizing each other's kingdoms. This allowed Harald to turn his attention to his ultimate ambition: the English throne.

Harald launched a massive invasion of England with 300 ships and 9,000 warriors, allied with the disgraced English earl Tostig. He defeated English forces at the Battle of Fulford and captured York.

Just days after his victory at Fulford, Harald was surprised by King Harold Godwinson's rapid march north. An arrow struck his throat, killing the last great Viking warrior king and ending the Viking Age.