In the Treaty of Choszczno (sometimes Treaty of Arnswalde), signed on 1 April 1269, the Brandenburgian Margrave

Margrave

A margrave or margravine was a medieval hereditary nobleman with military responsibilities in a border province of a kingdom. Border provinces usually had more exposure to military incursions from the outside, compared to interior provinces, and thus a margrave usually had larger and more active...

s of the House of Ascania John II, Otto IV and Conrad signed a treaty with Duke Mestwin II of Pomerania (Mściwój II) in Choszczno

Choszczno

Choszczno is a town in West Pomeranian Voivodeship, Poland. The town is located in a marshy district between the river Stobnica and Klukom lake , southwest of Stargard Szczeciński and on the main railway line between Szczecin and Poznań...

 (Arnswalde). The treaty gave them rights in Pomerelia

Pomerelia

Pomerelia is a historical region in northern Poland. Pomerelia lay in eastern Pomerania: on the southern shore of the Baltic Sea and west of the Vistula and its delta. The area centered on the city of Gdańsk at the mouth of the Vistula...

, including Świecie

Swiecie

Świecie is a town in northern Poland with 25,968 inhabitants , situated in Kuyavian-Pomeranian Voivodeship ; it was previously in Bydgoszcz Voivodeship . It is the capital of Świecie County.-History:...

 (Schwetz) and Białogard (Belgard).

In turn they had to finance the duke, e.g. for the marriage of Mestwin's daughter Katarzyna with Przybysław II of Parchim

Parchim

Parchim is a town in Mecklenburg-Vorpommern, Germany. It is the capital of the Ludwigslust-Parchim district. It was the birthplace of Moltke, to whom a monument was erected in 1876. Founded about 1210, one branch of the family of the duke of Mecklenburg residence in Parchim during part of the 14th...

-Richenberg. In 1273 Mestwin paid Brandenburg feudal homage from the towns of Słupsk (Stolp) and Sławno (Schlawe). That way he was safe from his brother Wartislaw II of Pomerelia, because an attack on Mestwin would be considered as an attack on Brandenburg.

Through this treaty, the Margraviate of Brandenburg

Margraviate of Brandenburg

The Margraviate of Brandenburg was a major principality of the Holy Roman Empire from 1157 to 1806. Also known as the March of Brandenburg , it played a pivotal role in the history of Germany and Central Europe....

 gained direct access to the Baltic Sea

Baltic Sea

The Baltic Sea is a brackish mediterranean sea located in Northern Europe, from 53°N to 66°N latitude and from 20°E to 26°E longitude. It is bounded by the Scandinavian Peninsula, the mainland of Europe, and the Danish islands. It drains into the Kattegat by way of the Øresund, the Great Belt and...

. In 1308, it also led to the Teutonic takeover of Danzig.