What Was the Treaty of Stralsund?
The Treaty of Stralsund, signed on 24 May 1370, was the most important treaty in the history of the Hanseatic League. The treaty was the result of the League’s victory in the war of 1367–70 against the Danish king Valdemar IV, and it guaranteed the privileges of the Hanseatic merchants in Scandinavia for the next two centuries. The treaty was, by any measure, the high point of the League’s commercial and political power, and it remained the foundation of the League’s commercial dominance of the Baltic until the late fifteenth century.
The war
The war that led to the treaty began in 1367, when the League’s cities of the Wendish and Prussian districts formed a coalition against the Danish king. The king had been trying to reimpose control over the herring fisheries of the Sound and to revoke the privileges of the Hanseatic merchants in Scandinavia, and the cities of the League decided they had to act. The coalition organised a fleet — sources put the size at roughly 200 vessels, though the exact number is debated — and the fleet sailed into the Sound, blockaded Copenhagen, and forced the king to negotiate.
A useful contemporary detail: the blockade of Copenhagen was a commercial blockade as much as a naval one. The Hanseatic fleet cut off the Danish capital from its supply of grain and salt — the two commodities on which the city most depended — and the blockade was effective because the Danish supply routes were, in 1368, almost entirely Hanseatic. The king was, in effect, starved into negotiating. The episode is one of the most successful pre-modern commercial blockades on record.
The treaty
The negotiations took place in Stralsund, and the treaty was signed on 24 May 1370. The principal provisions were:
- The Danish king recognised the privileges of the Hanseatic merchants in Scandinavia, including the right to trade freely in the herring fisheries of the Sound, the right to be exempt from most customs duties, and the right to be judged by Hanseatic law in disputes with the Danes.
- The Danish king agreed to consult the League on matters of commerce, and the League was given a substantial role in the governance of the herring fisheries of the Sound.
- The Danish king agreed to pay a substantial indemnity to the League.
- The Danish king released the Hanseatic merchants taken prisoner during the war, and the League released the Danish prisoners in its custody.
- The Danish king agreed to renew the existing treaties, which were to remain in force for the next two centuries.
A note on dating: the principal treaty’s provisions held for about 60–70 years rather than 200. The next major war with Denmark (1426–35) produced the Treaty of Vordingborg as a renewal rather than as a wholesale renegotiation, so the basic structure held; but by 1500 the Danish king was treating the treaty’s provisions as starting points for negotiation rather than as fixed terms. The “next two centuries” claim is the League’s own; the actual duration of the treaty’s effective operation is shorter.
A remarkable document
The Treaty of Stralsund was, by any measure, a remarkable document. It was the first time a great king had been forced to submit to a coalition of merchants, and it was the first time a great power had been forced to recognise the privileges of a foreign commercial organisation. The treaty was, in effect, a capitulation by the Danish crown to the League, and it marked the beginning of a new era in the history of northern Europe.
The treaty was, however, also a fragile victory. The League’s commercial dominance rested on the treaty’s provisions, and the provisions could be revoked by a hostile Danish king. The League had to maintain its military power to defend the treaty’s provisions, and the League’s failure to maintain its military power in the late fifteenth century was one of the reasons for the League’s decline.
A useful comparative: the Treaty of Stralsund is sometimes compared to the Treaty of Medina del Campo (1489) between Castile and Portugal, or to the English Carta Mercatoria of 1303. The Stralsund treaty is, however, distinctive in that it was negotiated by the merchants themselves, not by kings acting on their behalf. The Danish king was a defeated party; the Hanseatic merchants were the principal authors of the terms. This makes Stralsund one of the few medieval treaties in which the merchant class is the legally recognised party to the agreement, not a private actor subject to royal protection.