King Harold approached Stamford Bridge from the west, setting a rapid pace in his march. The Vikings were taken completely by surprised, at first not recognising what the shimmering in the distance was: the sunlight reflecting from the English mail and shields. Recognising that they were heavily outnumbered the Vikings had the choice of flight back to their ships or to make a stand. According to the later sagas the warlike Hardrada chose to fight and immediately sent three horsemen back to the fleet at Riccall, for reinforcements and the chain mail the Vikings had elected not to wear in the warm sun. Although camped on both sides of the River Derwent, Hardrada chose to deploy his main force on the eastern bank, thereby forcing Harold to make a crossing. Hardrada instructed the troops on the western bank to hold Harold for as long as possible giving the Vikings on the east bank time to deploy. But those holding the crossing were quickly overwhelmed and pushed back across the river.
The Anglo Saxon Chronicle relates the next phase, recording the exploits of a Viking hero single-handedly holding the entire English army at bay on the entrance to the bridge. Apparently impervious to arrows and spears this giant of a man was finally laid low by an Englishman whilst floating in a tub under the wooden bridge. His strategically aimed spear thrust, from below through the planks of the bridge, where the Viking was unprotected by his mail. The Norwegian Sagas are curiously silent on this episode.
Little detail of the battle is given in the Norwegian Sagas or the Anglo Saxon Chronicles, but it appears that the action was fierce and bloody but not necessarily prolonged. The English had the element of surprise and superior numbers, though also weary from days of forced marching. Nethertheless, they quickly gained the upper hand and the Vikings, finally unable to maintain their battle array, were broken into small bands that were quickly surrounded and destroyed. Hardrada was killed, giving impetus to the English but not signalling the end for the Vikings. Tostig was also slain.
Reinforcements from the Viking fleet were unable to save the day. The Viking army fled the field and were pursed back to Riccall, many dying in the flight. But Harold granted quarter to Prince Olaf, allowing him and the remnants of the Viking army to return to Norway after forcing him to promise never to invade again.