This had led to proposals that it should be replaced by a more modern fortress on the island of Kyrkogårdsholmen, which was a more easily defensible location and would also, being closer to the mouth of the Göta Älv, provide better protection for the new city at Gothenburg.

[4] In May 1645, during the Torstenson War, the Danish admiral Ove Gjedde launched an attack on Gothenburg with 20 ships, but the city was successfully defended by a Dutch squadron in Swedish service commanded by Martin Thyssens, who was subsequently ennobled as Lord Anckarhjelm.

[6] Bad weather and lack of money meant that progress was initially slow,[7] and the fortress was still unfinished when Karl Gustav's War against Denmark-Norway broke out in 1657, but it was nevertheless pressed into service with cannons transferred from Old Älvsborg.

Rodsten subsequently anchored his flotilla in the Gothenburg Archipelago in order to blockade the city, but the 42-gun ship København (Copenhagen) ran aground off the island of Grötö and had to be scuttled by her crew.

[11] See main article: Battles at Göta Älv During the final few years of the Great Northern War, Charles XII of Sweden attempted to revive his flagging fortunes by mounting repeated invasions of Norway from Bohuslän.

In order to reduce the powerful Norwegian fortresses at Fredriksten and Akershus, the Swedish army required a large siege train, which could only be transported by sea, and the charismatic Norwegian captain Peter Tordenskjold thus saw an opportunity to hamper Charles's plans by harassing the Swedish naval forces based at Gothenburg, thereby making it impossible for the siege train to be brought north.

On July 19 and 20, Tordenskjold gathered his forces in the Gothenburg Archipelago, comprising seven ships of the line, two frigates, four galleys, three floating batteries, and four barges as troop transports.

Protected by the Danish-Norwegian warships, the floating batteries approached Nya Älvsborg and began to bombard it, while the barges landed troops and mortars on the Aspholmar, a string of islets in the river directly to the north of Kyrkogårdsholmen.

[16] On 24 July, troops of the Skaraborg Regiment commanded by Georg Bogislaus Staël von Holstein managed to set up cannons on the south side of Hisingen, from which they could begin counter-battery fire against the Danish-Norwegian mortars in Aspholmarna.

However, shortly thereafter three Swedish galleys from Nya Varvet, the Carolus, Wrede and the Lucretia, managed to mount a seaborne attack on the Aspholmarna batteries, capturing four mortars, 60 bombs and three barrels of gunpowder.

A custom arose whereby each ship passing Nya Älvsborg was obliged to make a small gift to the commander of the garrison, often a bottle of wine or spirits; as such this posting became highly coveted, and was generally given to retired army officers as a sort of sinecure.