March Across the Belts

The crossing of the Great Belt

The March across the Belts was a campaign between January 30 and February 8, 1658 during the Northern Wars where Swedish king Karl X Gustav led the Swedish army from Jutland across the ice of the Little Belt and the Great Belt to reach Zealand (Danish: Sjælland). The risky but vastly successful crossing was a crushing blow to Denmark, and led to the humiliating Treaty of Roskilde later that year.

Background

King Charles X of Sweden was bogged down in his war with Poland, unable to reach a decisive conclusion to the hostilities despite taking Warsaw. A way out was provided when king Frederick III of Denmark declared war on Sweden. The Swedish army could now be marched to Denmark from Poland without making it look like a rout. Forced marches, amounting to several tens of kilometers a day, took 6,000 Swedish soldiers to Jutland. The army wasn't large but these soldiers were some of the best equipped and trained troops Europe had seen until then. The army swept away the Danish resistance; no one dared to commit to a pitched battle with the "invincible" Swedes.

On August 25, 1657 the Swedish army stood before the newly completed Danish fortress Fredriksodde on Jutland's east coast. The fortress had a complement of about 8,000 men. This fortress hadn't existed in 1645 (the last time Charles had been there). Fredriksodde was besieged by general Karl Gustav Wrangel for two months, and then stormed on the night of October 24. Few Swedes perished and 6,000 Danes were captured. In addition the Swedish army now had all of the Jutland army's supplies.

All of Jutland was soon under Swedish control and the king started preparations for an attack against the Danish islands. In the middle of December the weather shifted, turning into the coldest winter in memory. The seawater between the islands froze, making a shipborn assault impossible. Engineer Erik Dahlberg was dispatched by the king to ascertain whether the ice would support the weight of the Swedish cavalry and artillery. Dahlberg reported that a crossing over the ice was feasible.

The Crossing

Early in the morning of January 30, 1658, the army was lined up to cross the Little Belt to reach Fyn. The army consisted of about 9,000 cavalrymen and 3,000 foot soldiers. The ice warped under the weight of the soldiers; on occasions water reached up to the men's knees. Close to the shore of Fyn a skirmish broke out with about 3,000 Danish defenders, but these were brushed aside quickly and the army was safe on Fyn.

Now investigations were made to find the best way over the ice that covered Great Belt in order to reach Zealand. Again Erik Dahlberg led the investigation, and he advised taking the longer route via Langeland and Lolland rather than the more direct route across the Belt. The night of February 5 the king set off with the cavalry across the ice, and safely reached Lolland later in the day. The infantry and the artillery followed the next day. Thus, on the February 8th, the Swedish host was safely on Zealand, and on February 15th, after forced marches, it reached the outskirt of Copenhagen. The Danes, who had thought the Swedes would start their offensive in the spring at the earliest, panicked and yielded. Negotiations were started and on February 26 the Treaty of Roskilde was signed by the two parties.

Aftermath

The march across the Belts was a risky gamble entirely to King Charles' liking. The news of the victory spread quickly; it was an achievement that drew admiration all over Europe. For Denmark, the outcome of the treaty of Roskilde was disastrous: the entire eastern part of the country was ceded to Sweden and Denmark's existence as an independent state lay in doubt.

Source

• Herman Lindqvist, Historien om Sverige: När Sverige blev stormakt (1994)