Dag ruled the Swedes after his father. He was a very wise man who had the ability to talk to birds. Stories were told of a sparrow who flew to different countries and brought back news.
Once the sparrow flew to Reidgotaland, to a farm called Varva, where he flew
into the peasant's corn-field and took his grain. The peasant came up, took
a stone, and killed the sparrow. King Dag was ill-pleased that the sparrow
did not come home; and as he, in a sacrifice of expiation, inquired after
the sparrow, he got the answer that it was killed at Varva. Thereupon he
ordered a great army, and went to Gotland; and when he came to Varva he landed
with his men and plundered, and the people fled away before him. King Dag
returned in the evening to his ships, after having killed many people and
taken many prisoners. As they were going across a river at a place called
Skjotan's [the Weapon's] Ford, a labouring thrall came running to the
river-side, and threw a hay-fork into their troop. It struck the king on
the head, so that he fell instantly from his horse and died. In those times
the chief who ravaged a country was called Gram, and the men-at-arms under
him Gramer.
Heimskringla, Ynglinga Saga, Section 21
Dag the Wise or Dagr Spaka (2nd or 3rd century AD) was a mythological Swedish king of the House of Ynglings. He was the son of Dyggve, the former king.
Dag was so wise that he could understand the song of birds. He consequently had a tame sparrow which flew to various countries and returned to him with tidings like Hugin and Munin to the wise god Odin.
Once the sparrow happened to land on a corn field in a place called Varva in Reidgotaland (considering the date and location, apparently Gothiscandza). The peasant who owned the field managed to hit the sparrow with a stone and killed him.
When the sparrow did not return, Dag was angry and sacrificed to the gods in order to have an explanation. He was told about what had happened and declared war on the Goths. He landed in Reidgotaland with a great army and pillaged the land causing people to flee.
After having killed many Goths and taken many prisoners, they were returning to their ships. As they crossed the river at a place called Skjotan's ford (the weapon's ford), a thrall came running and threw a hayfork into the Swedish troops. The hayfork hit Dag on the head and he fell dead from his horse.
http://en.wikipedia.org/wiki/Dag_the_Wise