late 15th century and protested. During the 15th century, when English traders and fishermen started to come to Iceland, it became a common practice among chieftains to buy cannons for defence against foreign ships and for internal conflicts. Other firearms, such as the hand gonne, known as haki or hakbyssa in Iceland, became popular as well. Lutheranism Since the king of Denmark had embraced Lutheranism in the early 16th century he had campaigned to convert his realms from Catholicism to Lutheranism. In the 1540s it was Iceland's turn: a Lutheran bishop was elected as the bishop of Skálholt diocese and bitter conflict ensued. Although the bloodshed didn't come close to that in the Civil War fought in the 13th century, it was still considerable as the bishops fielded armies of thousands, and even fought at Alþingi. In a bid to isolate Skálholt, Iceland's last Catholic bishop, Jón Arason of Hólar, attempted to cut its lines of communication to the Westfjords by invading the lands of Daði Guðmundsson. Although initially successful in capturing Sauðafell he was later defeated by Daði's army and captured with his sons. Jón Arason and his sons were then transported to Skálholt and beheaded there in 1550. A year later a Danish mercenary force mostly consisting of Landsknechts arrived to support the policy of conversion. Although no open warfare continued, the Danish king was still wary of an insurrection and ordered the destruction of all Icelandic arms and armor. Further mercenary armies, consisting of Landsknechts, are sent to carry out these orders over the following years. After that starts a period where Royal Danish forces are responsible for the defence of Iceland. The Royal Dano-Norwegian Navy patrols the coasts of Iceland, but mostly to prevent illegal trading rather than piracy. Some Icelandic sheriffs, however, manage to continue to maintain considerable retinues, especially in the Westfjords, where the Landsknechts were not as thorough in their search. Pirate raids The lack of weaponry among Icelanders made them more vulnerable to pirate attacks than before, although in some places, such as the aforementioned Westfjords, Icelanders managed to massacre foreign pirates. Icelandic officials complained about the raids in letters to the king and as a result many halberds were sent to Iceland by Royal edict. The halberd, known as atgeir or arngeir in Icelandic, became a signature weapon of Icelandic farmers. The king remained wary of the Icelanders, and refused to