Bohus Bang

Bohus Fortress was the principal stronghold, and indeed namesake of, the province of Bohuslän, which prior to the 1658 Treaty of Roskilde was part of the Kingdom of Norway. Bohus was also one of the two crucial fortresses, the other being Old Älvsborg in Swedish Västergötland, controlling traffic through the estuary of the Göta Älv River. This estuary was especially important for the Swedes because Halland and Skåne were part of Denmark at the time, and so the mouth of the Göta Älv was Sweden's only point of access to the North Sea.

In 1563, the Northern Seven Years War broke out between Sweden and Denmark-Norway, and Danish-Norwegian forces managed to seize control of Älvsborg in a lightning attack. With both Älvsborg and Bohus in Danish-Norwegian hands, the Göta Älv was closed to Swedish vessels, and as the Danish Belts were also now impassable to Swedish vessels, Sweden was thus cut off from the North Sea and by extension from the world beyond the Baltic Sea (and even within the Baltic Swedish trade was heavily constricted, as Poland-Lithuania and Russia were both hostile as well). The resulting loss of trade was crippling to the Swedish economy, and it thus became imperative for the Swedes to regain access to the North Sea by either retaking Älvsborg or capturing Bohus Fortress instead.

Bohus was therefore besieged no fewer than six times during the war; during five of these the garrison was commanded by the Danish officer Jens Holgersen Ulfstand [da]. The largest of the attacks on the fortress was made in spring 1566.

On 5 March the Swedish army broke camp and marched west from Alingsås^[1] under the command of Nils Andersson Boije [sv]. Among his senior officers were two prominent aristocrats, Nils Sture and Erik Stenbock. On 20 March the siege train arrived at Bohus and on the 23rd the bombardment of the fortress began from the hill of Fontinberget to the north.^[2] The Swedish artillery fired some 2820 rounds,^[3] successfully making a breach in the walls, and Nils Boije gave the order for the assault at 6 AM on either 26 March^[4] or 27 March^[3] (accounts differ as to the date of the attempted storming).

The Swedes assaulted the breach with ten fänikor (units of several hundred soldiers men each), but were thrown back three times by the defenders.^[3] On the fourth attempt the Swedes successfully forced the breach and then seized the so-called "Red Tower" (Swedish: Röde Torn) and planted a Swedish flag at the top.

Two of the defenders, Hans Sund och Jørgen Mekelberg^[2] volunteered to try to detonate the Red Tower's gunpowder magazine in a suicide attack, and the commander Jens Holgersen Ulfstand promised to provide for their families. Sund and Mekelberg succeeded in rolling a powder cart down to the magazine and then igniting it, causing a massive explosion which blew the Red Tower apart. A Danish chronicler wrote that 'the Swedes were thrown into the sky like crows or other birds, and not one of them came from there alive".^[4] It is reckoned that around 250 Swedish soldiers were killed in the explosion.^[5]

The explosion stopped the Swedish assault in its tracks, and the attackers were forced to retire and regroup. Despite their losses the Swedes continued the siege, but in the meantime Danish reinforcements under Daniel Rantzau were dispatched from Halland. Rantzau reached the Göta älv on 30 April, whereupon the invaders lifted the siege and withdrew to Västergötland. According to Danish reports, the Swedes had lost some 2300 men during the siege,^[1] while the Danish-Norwegian garrison had only lost 150, though its provisions and ammunition had been almost completely exhausted by the time the siege ended.^[1]