Jón Arason (1484 - 1550) was the last Roman Catholic bishop over Iceland, who was executed in his struggle against the imposition of the Protestant Reformation.
Jón became involved in a dispute with his sovereign, King Christian III of Denmark, because of the bishop's refusal to promote Lutheranism in Iceland. In this struggle he had the help of his illegitimate children, who fought with him in various battles. However his attempt to capture his greatest adversary, Daði Gudmundsson, at the Battle of Sauðafell led to himself being captured, along with his sons Ari and Björn. They were handed over to the king's bailiff and when trying to decide what should be done with them, Jón Bjarnason, priest and steward at Skálholt, is quoted as having said the following: ,,Öxin og jörðin geyma þá best" (e. the axe and the earth will serve them best).
Jón Arason and his sons were executed by beheading at Skálholt on the 7th of November 1550 and this monument was erected in 1912 in their memory, at the supposed place of their execution. It reads: Jón Arason biskup - ljet hjer lífið fyrir trú sína og ættjörð - 7. nóvember 1550 (e. Jón Arason bishop - died here for his faith and homeland - 7th of November 1550).
The cache is a small plastic container, please note that it is not hidden in or on the monument itself so no need to cross the chain fence! When originally placed, the cache contained a logbook, finder's instructions, a pencil and a travel bug.
FTF: Harpix and lynxalynx, congrats!
Source: Wikipedia and timarit.is