Battle of Stamford Bridge (1066) - Not nearly as well known as the Battle of Hastings, the Battle of Stamford Bridge played a very important role in that more famous conflict.  Taking place only three weeks prior (on September 25th) to the Battle of Hastings, it forced King Harold Godwinson of England to march his troops north and repel a Viking invasion led by King Harald Hardrada of Norway.  Although it was an invasion by the Vikings, King Harold's brother, Tostig Godwinson, participated in the battle of the side of Harald Hardrada, and contributed a number of troops of his own to the fight.  As King Harold's younger sibling, Tostig was not expected to ever sit on the throne; so what he could not inherit, he tried to take by force. He had tried unsuccessfully earlier that Spring to overthrow his brother, but was not powerful enough.  So he formed an alliance with the Vikings. Certainly Harald Hardrada had designs of his own on the throne of England, but the inevitable battle between Tostig and Hardrada would have to play out after Harold was eliminated.  The site of the battle was at Stamford Bridge, about 22 miles (35km) east of York.  After arriving on English soil in early September, Harald Hardrada had forced the submission of York on September 20th and was waiting at Stamford Bridge for hostages of the city to officially surrender themselves.  But King Harold arrived before that had happened.  He marched his army a grueling 200 miles in only four days and took the Vikings by surprise.  Harald Hardrada had not expected his opponent to come so far north so quickly.  He was well aware of the potential invasion of the Normans to the south (which eventually came) and had expected Harold to guard the southern shore of the island.  As a result, most of the Viking warriors had left their armour back at camp.  This left them at a distinct disadvantage.  However, they had no choice but to fight.

The details of the battle are incomplete, with the Anglo-Saxon Chronicle being a primary source.  The Vikings appear to have taken up a defensive position in the front line while the bulk of the army retreated across the bridge to the eastern bank of the Derwent River.  Those Norsemen who stood and bought time for the others were quickly cut down; but there is a legend that a single Viking axeman blocked the bridge and held off the entire English army until the bulk of his comrades made it safely across.  He killed 40 soldiers before he himself was finally killed.  By the time the English had made it across, the Vikings had formed a shield wall and prepared for the Saxon charge.  The English also formed a wall and the two sides collided.  The fact that the Norsemen did not have their armour appears to have been the difference in this close combat.  Eventually the injuries they sustained from the enemy's weapons wore them down.  The battle went on for hours, but finally, the Viking wall fractured.  Harald Hardrada was killed by an arrow to the throat and Tostig died in the fight as well.  But there was no time for the English to celebrate.  After a hard fought victory, news had reached Harold that the Normans had arrived.  He was forced to march his weary troops back south and defend the island against William the Bastard (aka Conqueror).