Stamford Bridge, Battle of (Sept. 25, 1066), ended an attempted invasion of England by Harald Hardrada, king of Norway, and Tostig, the brother of King Harold II of England. They sailed up the River Ouse with 300 longships to attack York. Harold II marched north and defeated the invaders after a fierce struggle. Both Harald Hardrada and Tostig were killed. Three days after the battle, William, Duke of Normandy, landed on the south coast of England and began the Norman Conquest of the country.