|Drawing by Jack Powning|
'Island Fights' were a part of the early Viking law-code. Essentially, it was a one-on-one duel, taking place on a small island. They could be to the death, or to first blood with the loser being ransomed. Generally, such fights were a last resort.
Near the end of The Saga of Gunnlaug Wormtongue, the eponymous 'hero' challenges his rival Hrafn to an island fight, as Hrafn married the woman that he loved. Since Gunnlaug is the challenger, Hrafn got to strike the first blow (that'll make you think about it before you challenge someone). As it happened, Hrafn struck such a heavy blow on Gunnlaug's shield that it snapped off the blade of his sword, the broken shard nicking Gunnlaug on the cheek. Immediately, both men claimed victory. Gunnlaug argued that his opponent was disarmed. Hrafn countered that Gunnlaug was wounded. The other men who had come to view the duel decided that the whole thing should be called off, and, soon thereafter, island fights were outlawed in Iceland.
Of course that didn't end the feud. A few years later, the two met again in Norway, where such duels were still legal. This time, Gunnlaug killed Hrafn, but was himself mortally wounded.