King Harold has spent mid-1066 on the south coast with a large army and fleet waiting for William to invade.
The bulk of his forces are militia who need to harvest their crops, so on September Harold had dismissed the militia and the fleet.
Learning of the Norwegian invasion, he heads north at great speed with his house carls and as many thegns as he has been able gather, traveling day and night.
He makes the journey from London to Yorkshire, a distance of about one hundred and eighty-five miles (three hundred and ten kilometers), in only four days, enabling him to take the Norwegians completely by surprise.
Having learned that Northumbrians had been ordered to send the additional hostages and supplies to the Norwegians at Stamford Bridge, Harold hurries on through York to attack them at this rendezvous on September 25.
Until the English army comes into view the invaders remain unaware of the presence of a hostile army anywhere in the vicinity.
The Vikings are at an enormous disadvantage.
Their army is divided in two; with some of their troops on the west side of the River Derwent and the bulk of their army on the east side.
They are not expecting English intervention, and since it is an unseasonably warm day for late September; they leave their armor behind at their ships.
The English army arrives and annihilates the Vikings, who fight a futile defense on the west side of the river.
By the time the bulk of the English army has arrived, the Vikings on the west side are either slain or fleeing across the bridge.
The English advance is then delayed by the need to pass through the choke-point presented by the bridge.
A later folk story has it that a giant Norse axeman (possibly armed with a Danish Axe) blocked the narrow crossing, and single-handedly held up the entire English army.
The Anglo-Saxon Chronicle states that this axeman cut down up to forty Englishmen.
He was only defeated when an English soldier floated under the bridge in a half-barrel and thrust his spear through the laths in the bridge, mortally wounding the axeman.
Whatever the delay, this has allowed the bulk of the Norse army to form a shieldwall to face the English attack.
Harold's army pours across the bridge, forming a line just short of the Norse army, locks shields and charges.
The battle goes far beyond the bridge itself, and although it rages for hours the Norse army's decision to leave their armor behind has put them at a distinct disadvantage.
Eventually, the Norse army begins to fragment and fracture, allowing the English troops to force their way in and break up the Scandinavians' shield wall.
Completely outflanked, Hardrada at this point is killed with an arrow to his throat and Tostig slain.
The Norwegian army disintegrates and is virtually annihilated.
In the later stages of the battle, the Norwegians are reinforced by troops who had been left behind to guard the ships at Ricall, led by Eystein Orri, Hardrada's daughter's fiancé.
Some of his men are said to have collapsed and died of exhaustion upon reaching the battlefield.
These men, unlike their comrades, are fully armed for battle.
Their counterattack, described in the Norwegian tradition as "Orri's Storm", briefly checks the English advance, but is soon overwhelmed and Orri is slain by a Saxon warrior.
The Norwegian army routs, pursued by the English army.
Some of the fleeing Norsemen drown in the rivers.
So many die in an area so small that the field is said to have been still whitened with bleached bones fifty years after the battle.
