Wikipedia
Gunrod or Gunrød was a Viking warlord from Norway, designated as " Sea-King" (Sækonungr), who was possibly a cousin or brother of Harald II of Norway. From his permanent bases in the Loire, Gunrod launched brutal raids along the Cantabrian coast, and in 968, with a force of a hundred ships, he settled in Galicia for a whole year. In March of 968, Gunderedo reached the gates of Compostela, where the bishop Sisnando Menéndenz was killed by an arrow at the Battle of Fornelos on March 29 of 968. The Vikings entered the city without resistance.
The Galician count of Visigothic descent Gonzalo Sánchez ended the Viking adventure in 970, when he launched an attack with a powerful army that defeated the Vikings in a bloody battle, and captured Gunderedo, who was subsequently executed along with his followers. The brutal response was probably a consequence of the Vikings at the time being a larger threat to the Spanish principalities than the Moors.