I have ancestors on both sides of the equation so I am not taking sides :-)
"Then he (Olav) sailed to Finland, landed and pillaged there, but all of the locals escaped into the forests and took all their possessions with them away from the area/region. The king ventured far inland and through some woods; there were valley regions called Herdalarna. They took some property, but no men. When evening drew near, the King began his way back to his ships. But when they returned to the woods, they were confronted by men from all sides, and harrassed and shot at fiercely. The King told his men to take cover/protect themselves. But before they could get out of the woods, he had lost many men and several were wounded. He arrived at the ships in the evening. In the night, the Finns created a great storm with their witch-craft. But the king ordered to lift up the anchor and raise the sails, and they travelled along the coast during the night. The King's good luck was then, like so often, more effective than the witch-craft of the Finns. They managed to sail along the coast of Balegard and then out to sea. But a band of Finnish warriors followed them on land as the king sailed along the coast."