Dano-Swedish War (1657–1658)

The Dano-Swedish War of 1657–1658, known in Denmark as the First Karl Gustav War (Danish: Første Karl Gustav-krig) in Norway as Krabbes Feud (Norwegian: Krabbefeiden) and in Sweden as Karl Gustav's First Danish War (Swedish: Karl Gustavs första danska krig), was a conflict between Sweden and Denmark–Norway during the Second Northern War. In 1657, Charles X of Sweden and his Swedish army were bogged down in Poland. Frederick III of Denmark-Norway saw an opportunity to recover the territories lost in 1645 and attacked Sweden. The outbreak of war with Denmark provided Charles with an excuse to withdraw from the Polish campaign and move against Denmark.

Bremervörde in Swedish Bremen-Verden under Danish attack in 1657.

Dano-Swedish War (1657–1658)
Part of the Second Northern War
The March Across the Belts. One of Swedens most strategic important and impressive military campaigns
Date 1657–1658 Location Scandinavia (Jutland, Danish Isles, Sweden, Halland, Jämtland, and Norway Danish Straits Result Decisive Swedish victory; Treaty of Roskilde/Treaty of Taastrup Danish renunciation of all anti-Swedish alliances. Danish prevention of any warships hostile to Sweden passing through the straits into the Baltic. Danish payment for Swedish occupation forces costs. Danish provision of troops to serve Charles in his broader wars.[1] Territorial changes Scania, Blekinge, Halland, Bohuslän, Bornholm and Trøndelag annexed to Sweden. Swedish Gold Coast temporarily occupied by Denmark–Norway Duke of Holstein-Gottorp Secures independence from Denmark[2]
Belligerents
Sweden	Denmark–Norway Poland–Lithuania[3] (The Deluge)
Commanders and leaders
Charles X Gustav Carl Gustaf Wrangel Gustaf Otto Stenbock Per Brahe the Younger	Frederick III Ulrik Frederik Gyldenløve Anders Bille  † Iver Krabbe

A harsh winter had forced the Dano-Norwegian fleet into port, and froze the Great Belt and Little Belt straits. After entering Jutland from the south, a Swedish army of 7,000 battle-hardened veterans marched across the icy Little Belt onto the Danish island of Funen on 30 January 1658. The Swedes captured the island of Funen within a few days and then sent on to capture the islands of Langeland, Lolland, and Falster. The Swedish army continued to Zealand, threatening the Danish capital of Copenhagen. The rapid Swedish attack across the frozen Belts was completely unexpected; Frederick III considered meeting the Swedish army in battle, but his advisors thought this was too risky and instead Denmark-Norway signed the very harsh Treaty of Roskilde on 26 February 1658.

Sweden had won its most prestigious victory, and Denmark-Norway had suffered its most costly defeat.[4] Denmark-Norway yielded the Danish provinces of Scania, Halland, Blekinge and the island of Bornholm and the Norwegian provinces Bohuslen and Trondhjem len (Trøndelag and Nordmøre) to Sweden. Halland had already been under Swedish control since the signing of the Treaty of Brömsebro in 1645, but it now became Swedish territory permanently.