Arkona, the Principality of Rügen became part of Kingdom of Denmark. In the course of German Ostsiedlung, many German settlers, gentry and merchants were invited to settle in the principality, and they eventually populated the Strale settlement. Merchants from other countries as well as locals were attracted to the area and made up one third of the settlement's population. The Danish navy used the isle as well. When the settlement had grown to town size, prince Wizlaw I of Rügen granted Lübeck law to "our town Stralow" in 1234, although a significant settlement had existed long before the formal founding. In 1240, when the prince gave additional land to the town, he called it Stralesund. The success of the settlement challenged the powerful Free City of Lübeck, which burnt Stralsund down in 1249. Afterwards the town was rebuilt with a massive town wall having 11 town gates and 30 watchtowers. The Neustadt, a town-like suburb, had merged with Stralsund by 1361. Schadegard, a nearby twin city to Stralsund also founded by Wizlaw I, though not granted German law, served as the principal stronghold and enclosed a fort. It was given up and torn down by 1269 under pressure from the Stralsund Bürger. In 1293 Stralsund became a member of the Hanseatic League. A total of 300 ships flying the flag of Stralsund cruised the Baltic Sea in the 14th century. In 1325 the Principality of Rügen became part of the Duchy of Pomerania, Stralsund however maintained a considerable independence. In the 17th century opposing forces in the Thirty Years' War fought over Stralsund. In the Battle of Stralsund (1628), the Imperial (Catholic) forces commanded by Albrecht von Wallenstein besieged the city after the council refused to accept the Capitulation of Franzburg of November 1627. Stralsund resisted with Danish and Swedish support. The Swedish garrison in Stralsund was the first on German soil in history. With the Treaty of Stettin (1630), the city became one of two major Swedish forts in the Duchy of Pomerania, alongside Stettin (now Szczecin, Poland). After the war, the Peace of Westphalia (1648) and the Treaty of Stettin (1653) made Stralsund part of Swedish Pomerania. Lost to Brandenburg in the Battle of Stralsund (1678), it reverted to Sweden in the Treaty of Saint-Germain-en-Laye (1679). In the Great Northern War in 1715 Charles XII led the defence of Stralsund for a year against the united European armies.