Treaty of Stralsund (1370): The Hanseatic League Defeats Denmark

The Treaty of Stralsund, signed on 24 May 1370 in the Baltic port of Stralsund, ended the war between King Valdemar IV of Denmark and a coalition of Hanseatic towns. Denmark confirmed the merchants’ privileges, handed them four fortresses in Scania for fifteen years and accepted their influence over the choice of the next king. The settlement is often seen as the high point of the power of the Hanseatic League.

Background: Valdemar IV and the Baltic towns

The Hanseatic League was a loose association of mostly German trading towns, led by Lübeck, that dominated commerce in the Baltic and North Sea. Its members depended on safe passage through the Danish straits and on access to the herring fairs of Scania, then a Danish province and the richest fishing market in northern Europe.

King Valdemar IV Atterdag had restored Danish royal power after decades of collapse. In 1360 he seized Scania from Sweden, and in 1361 he conquered Gotland after the Battle of Visby. He also raised tolls on shipping and challenged the merchants’ privileges.

The towns struck back in 1362, but their fleet was defeated near Helsingborg and a truce followed. Valdemar continued to harass Hanseatic shipping, convincing the towns that a broader alliance was needed.

The Cologne Confederation and the war

On 19 November 1367 representatives of Wendish, Prussian, Livonian and Dutch towns met in Cologne and formed the Cologne Confederation, an alliance for war against Denmark. They agreed to share costs, provide ships and men, and levy a toll on trade to pay for the campaign.

The towns found allies among Valdemar’s many enemies. King Albert of Mecklenburg, who ruled Sweden, the counts of Holstein and rebellious Jutland nobles joined the coalition. King Haakon VI of Norway, Valdemar’s son-in-law, was also at war with the Hanse.

In 1368 the allied fleet attacked the Danish coast, captured Copenhagen and damaged its fortifications, and besieged castles in Scania. Valdemar left the kingdom in spring 1368, travelling to Germany to seek support and leaving the government to the Council of the Realm under the steward Henning Podebusk. Norway made a truce with the towns in 1369.

The terms of the treaty

Negotiations led to the peace signed at Stralsund on 24 May 1370. Its main terms were:

• Confirmation and extension of the towns’ trading privileges throughout Denmark, including free trade and fixed tolls.
• Possession of the Scanian fortresses of Skanör, Falsterbo, Malmö and Helsingborg for fifteen years.
• Two-thirds of the royal revenues from those districts during that period.
• A promise that Valdemar’s successor would be chosen only with the towns’ consent.

The concession of the fortresses mattered most in practice. Hanseatic officials, appointed by the towns rather than the king, now guarded the herring markets where merchants from across northern Europe gathered every autumn. The revenue clause paid back part of the cost of the war, and the fixed tolls meant that Danish kings could no longer raise charges on the towns’ ships at will.

The succession clause was unusual. It did not give the towns a right to name the king, but it meant that any new Danish ruler would need to reassure them about their privileges before being accepted.

Valdemar, still abroad, eventually accepted the treaty and returned to Denmark in the early 1370s.

Consequences

The treaty gave the towns unprecedented political as well as commercial power. A merchant league without a single ruler or standing army had defeated a kingdom and secured a voice in its succession. The Scanian fortresses were returned to Denmark in 1385, as agreed.

The peace also strengthened Lübeck’s leadership. Meetings of town representatives, known as the Hanseatic Diet, became more regular in the following decades, and the towns grew used to acting together in politics as well as trade, even though they never formed a single state.

Valdemar died in 1375. His daughter Margaret secured the throne for her young son Olaf, and later united Denmark, Norway and Sweden in the Kalmar Union of 1397, creating a Nordic power that would again test the towns’ position. Hanseatic trade, including the stockfish business at Bryggen in Bergen, flourished in the decades after the peace.

Myths and facts

It is often said that Stralsund made the Hanse a state. In fact, the League never had a constitution, permanent government or fixed membership. The Cologne Confederation was a temporary alliance for one war, and it was formally dissolved in 1385 once its aims were met.

Timeline

• 1360: Valdemar IV takes Scania from Sweden.
• 27 July 1361: Valdemar defeats the Gotlanders at Visby and takes the town.
• 1362: The Hanseatic fleet is defeated near Helsingborg.
• 19 November 1367: The towns form the Cologne Confederation.
• 1368: The allies capture Copenhagen; Valdemar leaves Denmark.
• 24 May 1370: The Treaty of Stralsund is signed.
• 1375: Valdemar IV dies.
• 1385: The Scanian fortresses return to Denmark.

Why it matters

The Treaty of Stralsund showed that an alliance of merchant towns could defeat a medieval kingdom and dictate terms. It secured the Hanseatic grip on Baltic trade for generations and shaped the politics of Scandinavia on the road to the Kalmar Union.