At the Peace Treaty of Roskilde in 1658, Bohuslän became Swedish, but Bohus Fortress’ continued existence was anything but peaceful. Since its founding in 1308 the fortress has suffered 14 sieges, but has never been taken. When Sweden won dominion of Bohus, it was now the Danish and the Norwegians who tried to siege the fortress, but with no success.
The worst siege that ever occurred was in the summer of 1678, when 15 000 Danish and Norwegian attacked the 800 Swedish and Finnish defenders during a massive bombardment that lasted two months.
Swedish reinforcements arrived in the knick of time and the enemy ceased the attack. Bohus was almost completely ruined and its former glory was only a shadow compared to when this ancient Renaissance Fortress was first built as a stronghold under the leadership of Erik Dahlberg. No more sieges occurred and during the 1700’s Bohus Fortress served primarily as a prison.
The Theatre War
In 1786 the final Swedish garrison withdrew, but two years later Bohus Fortress was occupied again by invading Danish/Norwegian troops during the so called ”Theatre War.”
Sweden survived the war but were frightened by it, for they realised that an unguarded fortress could potentially cause more harm than good. Therefore in 1789, a proposal to demolish Bohus Fortress was put forth, with the approval of King Gustaf III. Thus ended an almost 500 year span as a defence facility.