In January 1066, Edward the confessor die. After this traumatic event, Edward's distant cousin William, Duke of Normandy thought he should be crowned king
Let's go kill him
However, Harold Godwinson was crowned king. William was obviously not pleased with this and was very upset. Another man called Harold Hardraada wasn't happy about this either because he wanted to be king
Harold Hardraada decided to fight back. On 25th of September 1066, Harold Godwinson defeated Harold Hardraada in the battle of Stamford Bridge
I am finally king
At the end of September 1066, William, Duke of Normandy sails to England from France with his very large army. While William was heading to England, Harold Godwinson heard about this and decided to go south with his army.
On the 14th of October 1066, William and his army met Harold and his army at Senlac hill to do a battle. Thousands of men were killed and eventually, William won by defeating Harold and his army. It is said that Harold was killed by an arrow in his eye.
Since that battle, people in England gave William of Normandy a nickname which was William the Conqueror. On the 25th of December 1066, William of Normandy was officially crowned king.