Zrin Castle was first mentioned in the 13th century as a fortress ruled by the Babonić clan. Between 1328 and 1347, it was possessed by the members of Iločki family. In 1347, King Louis I the Great bestowed the fortress to the noble Šubić family who then changed their family name after it, becoming the Zrinski. It remained in their possession until the Ottoman invasion and conquest of the region, which led to the fortress falling to them on 20 October 1577. It wasn't until 1718 that the castle was retaken from the Ottomans.
References:Carlsten is a stone fortress built on the orders of King Carl X of Sweden following the Treaty of Roskilde, 1658 to protect the newly acquired province of Bohuslän from hostile attacks. The site of Marstrand was chosen because of its location and its access to an ice free port. Initially a square stone tower was constructed, but by 1680 it was reconstructed and replaced by a round shaped tower. Successive additions to the fortress were carried out, by the inmates sentenced to hard labour, until 1860 when it was reported finished. The fortress was decommissioned as a permanent defense installation in 1882, but remained in military use until the early 1990s.
The fortress was attacked and sieged twice falling into enemy hands. In 1677 it was conquered by Ulrik Frederick Gyldenløve, the Danish military commander in Norway and in 1719 by the Norwegian Vice-Admiral Tordenskjold. At both occasions the fortress was returned to Swedish control through negotiations and treaties.