On June 8, 793, Viking longships appeared off the coast of Northumbria and attacked the monastery at Lindisfarne, known as the 'Holy Island.' The raiders killed the monks and looted the monastery's treasures, including gold-covered gospels. This event sent shockwaves through Christian Europe, as it was the first time a major religious site had been targeted by 'heathen' invaders from the North. For historians, the Lindisfarne raid marks the traditional beginning of the Viking Age. It established the Viking reputation for ferocity and showcased the tactical advantage of their shallow-draft longships, which allowed them to strike deep inland via rivers and retreat before a local defense could be organized.