How did someone end up with an arrow in their eye in the Battle of Hastings?

They looked up.

King Harold (the Anglo-Saxon king of England) had formed his men up on a low ridge in the traditional "Shieldwall". From this position they were able to repulse several attacks by William's Norman invasion forces. Throughout the battle the shield wall was being fired on by archers, but in this period arrows weren't all that dangerous to a fully armoured huscarl. He would be wearing chainmail, padding and a helmet as well as his shield.

Unfortunately Harold looked up. Lucky shot...