Bohus Fortress lies in Kungälv, Bohuslän, Sweden, north east from Hisingen where the Göta river splits into two branches ( north of Gothenburg). It commands the surrounding area from a cliff high, with the river forming a natural moat around it. The fortress used to be situated along the old Norwegian–Swedish border.
Initial construction
The construction of Bohus Fortress (, ) began in 1308 under King Haakon V Magnuson, king of Norway from 1299 to 1319. Håkon V also initiated construction of Norwegian fortresses at Akershus and Vardøhus as part of a broader defensive policy. At the time Bohuslän (Båhuslen) was Norwegian territory and served as the main Norwegian defence against Sweden, along the coast as well as the strong point for the Bohuslän region from 1308 to 1658.
thumb|300px|Bohus Fortress
Medieval castle
According to architect Guthorm Kavli:
Fortress
left|thumb|240px|Picture of model of Bohus Fortress, as it was before it was ceded to the Swedes
The fortress was attacked or besieged 14 times, but was never captured. They gave Henrik Gyldenstierne, Captain of Bohus, a ring and a gold chain worth 3,000 Danish dalers. Gyldenstierne gave James a firearm and a sword.
In 1593–1604, similar to the construction then undertaken at Akershus in Oslo, Bohus was upgraded to a bastion fortress. A new outer fortification was raised. This construction was one of the early works of Hans van Steenwinckel, also from the Netherlands, who later became noted for his Dutch Renaissance style design in Denmark.
As Swedish invasions continuously threatened Norwegian Båhuslen during this time period, the improvement of the fortifications went on for years. For example, starting in the summer of 1651 and until the autumn of 1652, the Dutch engineer Isaac van Geelkerck supervised the construction of two corner towers along the south façade and a new ring wall that was constructed around the arsenal building.
Loss to Sweden
Under the terms of the Treaty of Roskilde in 1658, Denmark–Norway ceded the Danish provinces of Scania, Blekinge and Halland (the latter was agreed to belong to Sweden for a period of 30 years after the Peace of Brömsebro, but was given to Sweden permanently in the treaty of Roskilde) and the Norwegian provinces Trøndelag and Bohuslän (including the Bohus Fortress).
Last Siege
After an unsuccessful attempt to recapture the fortress in 1676, a Norwegian army under the command of Ulrik Frederik Gyldenløve returned in June 1678 and besieged it again. Some 850 defenders faced 16.000 attackers, who fired 20-30.000 iron gun shots, 2265 "bombs" with chemical and biological content, 384 explosive grenades, 384 "great stone boulders", 161 glowing fire shots, 79 sacks filled with grenades and 600 "great mortar rounds". Also a number of mines was exploded under the outer walls. After six weeks of constant battering, the fortress was saved by an approaching Swedish detachment. At this time, there was 400 survivors in the fortress, 300 dead, and 120 wounded "who had their arms and legs shot off". The fortress itself was almost completely ruined and the repairs went on for some 50–70 years, but with small financial support and only the most important work was done.
After Denmark–Norway ceded the territory which included Bohus Fortress, Fredriksten Fortress was constructed in Fredrikshald on the newly established Norwegian-Swedish border.
Since the Bohus Fortress no longer lay on the border, it was of small use to Sweden,
thumb|750px|center|Panorama from the Bohus Fortress of the Göta river dividing into Göta river and Norder river (down right)
See also
- Siege of Bohus fortress (1678)