[5] From the naval base at Gravningsundet in Hvaler, Fisker's task was to act as a hedge against Swedish movements by sea, at the same time as he were to support a possible offensive into Sweden.

Several raids were also conducted by the Norwegians from their base at Gravningsundet, and during a reconnaissance mission outside Strømstad on the morning of 20 April, Fisker had sent a troop of sailors and infantry towards Seläters pier south of Svinesund under cover of darkness.

This gave him time to prepare for a possible attack against Strömstad, so he ordered the creation of a land battery at Furuholm, which guarded the (approximately) 200 meters wide entrance to the harbour.

[citation needed] Lorents Fisker began his attack on Strömstad on 28 April, but was met by Captain Nordberg and his five large gun sloops who pulled up to the middle of the entrance at Furuholm.

The Swedes had chosen a good place to defend the entrance, and along with the land battery, they held out against the Danish-Norwegian fleet which in the narrow waters failed to exploit their numerical superiority.