A terrible storm hides foreign longships looming at the shore. From them, bearded men armed with spears, axes, and shields invade a Christian monastery.

They break the doors, cut down the monks, and steal all the precious metals they can carry. Before the guards arrive, they've set sail.

That's a business-as-usual Viking raid during the Sixth Century when the Vikings terrorized the English Kingdoms in search for money and glory.

Why were the Vikings so savage at their raids? And what made them so sucessful?