Harold Godwinson waited at the south coast for William of Normandy
Harold received a message to say Harald was invading in the north so he had to march back 300Km in 5 days to Stamford Bridge
Harald Hardrada and Tostig ( Harolds brother) set up camp at Stamford bridge after taking over York.
Haradrada was surprised when Horolds army turned up, and he wasnt prepared he had left 1/3 of his men guarding the boats and they had left their armour behind.
A viking named Berserka was defended the only bridge across the River Derwent which was separating the two armies. He killed 40 soldiers before a clever soldier swam under the bridge and attacked him from below.
Harolds army defeated Haralds viking army killing both Harald and Tostig in the process. Harold allowed the remaining vikings to go back home as long as they promised not to invade again and to be Harolds ally if he needed him in the future.