When Gustav III of Sweden on his own initiative, and unconstitutionally, attacked Russia in 1788 and thereby started the Russo-Swedish War of 1788–90, Denmark-Norway found itself in an awkward position.

He left the battlefront in Finland and proceeded to Stockholm and then Dalarna where he managed to incite several free corps to participate in the defense against the Danes and Norwegians.

The first Danish-Norwegian force of about 8,000-10,000 men under the command of Prince Charles of Hesse attacked Bohuslän from Norway on 24 September and advanced quickly toward Vänersborg meeting feeble Swedish resistance.

Colonel Johan Werner Tranefelt ensconced himself in Kvistrum north of Uddevalla with his 700 men but was defeated on 29 September by a much larger Danish–Norwegian force led by Major General Johann Friedrich von und zu Mansbach.

Faced with the armistice, threats of a joint attack on Holstein from both Great Britain and Prussia, and an ever more strongly defended Gothenburg, the Danish–Norwegian troops marched off on 12 November 1788 toward Norway, and Gustav III could use this as an excuse to call it a victory.

The success could have turned into a debâcle when it was revealed that a lieutenant Benzelstjärna with the king's approval had planned to burn the seven Russian ships in the Copenhagen harbor.

The almost frivolous Swedish and Norwegian names for the conflict do not reflect the real suffering caused by it: the Danish–Norwegian army lost 1,500-3,000 men to hunger, disease, poor sanitary conditions, and exposure to continual autumn rainfall.