The Battle of the Sound, 1658: Why Amsterdam Fought for Denmark

In November 1658 a Dutch fleet fought its way into the Sound to save Copenhagen from Sweden.

11 October 2026 · Part of Dutch Republic & VOC — a guide to 12 articles →

On 8 November 1658 a Dutch fleet under Jacob van Wassenaer Obdam forced its way through the Sound and broke the Swedish blockade of Copenhagen. The Republic had no love for Denmark and little for its king. It fought because the narrow water between Zealand and Scania was the gate to the Baltic, and the Baltic was where Amsterdam earned its living.

The gate to the Baltic

The Sound, the strait at the eastern end of the Danish islands, was the busiest chokepoint in northern Europe. Almost every ship sailing between the North Sea and the Baltic passed it, and Denmark charged a toll on the cargo at Helsingør. Dutch ships carried most of that traffic: rye and wheat from Poland and the Baltic coast, timber, tar, hemp and iron going west, and salt, herring, cloth and wine going east.

That trade is the reason the Republic could feed its towns while its farmers raised cattle and flax. Historians such as Jonathan Israel have long treated the Baltic "mother trade" as the foundation of Amsterdam's wider commerce, which is why a threat to the Sound was treated as a threat to the city itself. The older medieval order that once governed these waters is described in our piece on the Hanseatic League; by the 1650s Dutch skippers had largely taken its place.

The Dutch did not want Denmark to be strong. They wanted nobody to be strong enough to close the strait. A weak, toll-taking Denmark that could be bargained with suited them better than a Sweden holding both shores.

How Sweden got there

Sweden's king Charles X Gustav had spent the 1650s fighting in Poland, then turned on Denmark in 1657. In the winter of 1657-58 his army crossed the frozen Belts to Zealand, a march that astonished contemporaries. Denmark sued for peace, and the Treaty of Roskilde of February 1658 forced it to give up Scania, Halland, Blekinge and Bornholm, together with Norwegian territory around Bohuslän and Trondheim.

For the Dutch, the alarming part was geography. Once Scania was Swedish, Sweden held the eastern shore of the Sound and the king still hankered after the western. In the summer of 1658 he resumed the war, landed on Zealand and besieged Copenhagen. If the city fell, Denmark would cease to be a power, and the Sound would belong to Stockholm.

The relief fleet

The States General sent a fleet to the Sound under Wassenaer Obdam, with Witte de With as vice-admiral. Our account of Witte de With covers the man; here the point is the machinery behind him. The ships came from several of the Republic's colleges of admiralty, the semi-independent boards described in our guide to the five Admiralties, and the expedition was driven in no small part by the merchants of Amsterdam, whose admiralty paid for much of the effort.

The fleet sailed in the middle of October and reached the approaches to the Sound early in November, with soldiers aboard for the besieged city.

The battle

The Swedish fleet under Carl Gustaf Wrangel lay off the strait. Sources give the Dutch about 41 ships and the Swedes about 45, though counts of ships and guns vary between accounts, and the numbers should be treated as approximate. The Dutch sailed in three squadrons and the Swedes in four.

The date also differs by source. The battle is usually given as 8 November in the New Style calendar used on the Continent, which was 29 October in England and Sweden, and both dates appear in the literature.

A small Danish squadron was present but, according to the accounts we have read, was held back by contrary wind and could only watch. The fight was therefore Dutch against Swedish. The Dutch pressed through the narrows and engaged the Swedes in close, hard action. Witte de With's flagship Brederode ran aground and was lost along with its admiral; the Rijksmuseum's large painting of the battle shows the Eendracht engaged with two Swedish warships. Casualties are commonly put at roughly 1,400 for the Dutch and 1,200 for the Swedes, with one Dutch ship lost and several Swedish ships captured. These are the figures of the standard summaries, not of a careful modern count.

By nightfall the Dutch held the water in front of Copenhagen. Reports say that around two thousand Dutch soldiers and a quantity of supplies were landed in the city, and the Swedes pulled back from their forward positions.

Chronology

Why a Dutch victory was not Dutch conquest

What the Republic did next is as telling as the battle. It did not seize Danish territory, take over the toll, or set up a base on the Sound. Its aim was a balance. Together with England and France it backed the Concert of The Hague in 1659, which urged a peace built on Roskilde but with the Sound kept open to shipping, and the Treaty of Copenhagen in 1660 largely followed that line.

The result was a settlement that served Amsterdam without making it a conqueror. Sweden kept the Scanian provinces and so a coast on the Sound, but it did not take Copenhagen; Denmark kept its capital and its toll. A century of Dutch policy had aimed at this outcome, and 1658 was the one occasion on which the fleet had to be used to secure it.

The episode also shows the limits of Dutch sea power. The relief worked because the Republic could mobilise a large fleet quickly for a clear purpose. Fourteen years later, in the crisis told in the disaster year of 1672, the same state was fighting for survival on land and sea at once. A comparison with the Company's wars in Asia, such as Cape Rachado in 1606, shows how differently the Republic fought when its core interests, not its Company's, were at stake. The commercial empire behind both is explained in our history of the Dutch East India Company.

Our record of Dutch Golden Age sea battles lists the Sound among the actions of the century, and it is one of the few in which the Republic fought openly to prevent a rival from controlling trade rather than to win it for itself.

Conclusion

The Battle of the Sound was a short, bloody action with a durable result. It did not make Denmark a friend or Sweden an enemy of the Republic; it kept a strait open. Amsterdam's merchants had learned that the cheapest way to protect a trade empire built on bulk cargo was to prevent any single power from owning its chokepoints, and in November 1658 they paid for a fleet to prove it.

Frequently asked questions

Why did the Dutch Republic intervene on Denmark's side? The Republic's Baltic trade passed through the Sound, and Sweden controlling both shores would have let it tax or close that passage. Denmark was not so much an ally as the lesser danger.

Who won the Battle of the Sound? The Dutch, in the sense that matters: they reached Copenhagen and ended the sea blockade. Losses on both sides were heavy, and the Dutch lost Witte de With.

Did the Dutch take anything from the war? No territory. They secured a peace in which the Sound stayed open, which was the whole purpose of the expedition.

Why are the dates given differently? The Continent used the Gregorian calendar while England and Sweden still used the Julian one, so the battle falls on 8 November in one and 29 October in the other.

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