Siege of Stralsund ( 1628 ) The Siege of Stralsund was a siege laid on Stralsund by Albrecht von Wallenstein ' s Imperial Army during the Thirty Years ' War , from May to 4 August 1628 . Stralsund was aided by Denmark and Sweden , with considerable Scottish participation . The siege ended Wallenstein ' s series of victories , and contributed to his downfall . The Swedish garrison in Stralsund was the first on German soil in history . The battle marked the " de facto " entrance of Sweden into the war . Prelude . Belligerents . Christian IV of Denmark had declared war on the Holy Roman Empire in 1625 . He had then invaded the empire with an army commanded by Ernst von Mansfeld to oppose the Catholic League ' s army commanded by Johann Tserclaes , Count of Tilly . In response , Ferdinand II , Holy Roman Emperor , had Albrecht von Wallenstein raise an additional army to support Tilly . Wallenstein defeated Mansfeld in the Battle of Dessau Bridge in 1626 . The remnants of Mansfeld ' s army left Central Germany , and turned to Silesia and Hungary to regroup with Gabriel Bethlen ' s forces . After Tilly had defeated Christian IV in the Battle of Lutter am Barenberge in August 1626 , and Bethlen was neutralized in the ( third ) Peace of Pressburg in December , Tilly and Wallenstein were able to subsequently expel Christian IV from the North German plain , organized in the Lower Saxon and Upper Saxon imperial circle s , and pressure him even in Danish Jutland . The internally divided Upper Saxon circle , to which the Duchy of Pomerania with Stralsund belonged , was uncapable of self - defense and had formally declared neutrality . Christian IV ' s army staff heavily relied on Scottish expertise : with 300 Scottish officers in his service , Scottish officers outnumbered Danish and Norwegian officers combined by 3 : 1 . Also , Christian IV had issued patents to raise 9 , 000 Scottish troops in 1627 , adding to 2 , 000 - 3 , 000 Scottish troops raised by Donald Mackay for Ernst von Mansfeld ' s army , but who had been deployed to Denmark instead . Gustavus Adolphus of Sweden was since 1626 involved in the Polish - Swedish War , with Poland allied to the Holy Roman Empire . In this war , Scotsman Alexander Leslie started his career in Swedish service as commandant and governor of Pillau in East Prussia . Gustavus Adolphus had made plans to intervene in the Holy Roman Empire , of which the Riksdag commission approved in the winter of 1627 / 28 . Situation in Pomerania . In November 1627 , the Duchy of Pomerania had capitulated to the forces of the Holy Roman Empire . Bogislaw XIV , Duke of Pomerania , on 10 November signed the Capitulation of Franzburg with Hans Georg von Arnim , who on behalf of Albrecht von Wallenstein commanded the imperial occupation forces in Pomerania . With the occupation , Wallenstein sought to secure the southern coastline of the Baltic Sea for Ferdinand II , Holy Roman Emperor against Christian IV of Denmark . The Capitulation of Franzburg required all towns except for ducal residences to take in imperial troops , and Wallenstein had ordered Arnim to occupy the Pomeranian ports and seize their vessels already in October . Stralsund however was unwilling to give in , as its status as a Hanseatic town had provided for considerable self - determination and independence from the Pomeranian dukes . Thus , Stralsund ignored Bogislaw ' s order to adhere to the capitulation , issued since February 1628 , and instead turned first to Denmark and then to Sweden for support . Siege . Starting in May 1628 , siege was laid on Stralsund by Albrecht von Wallenstein ' s troops , commanded by Hans Georg von Arnim . By then , the town with its 20 , 000 inhabitants was defended by a citizen force of 2 , 500 , a levy of 1 , 500 , and another 1 , 000 enlisted men . The first major imperial assault on the city took place between 16 and 24 May . Christian IV of Denmark had reacted positively to Stralsund ' s call and deployed a force including 900 of Mackay ' s Scotsmen , organized in seven companies , and a company of Germans in her defense . Though dispatched already on 8 May , they only landed on 24 May . Initially , the Danish - German mercenary Heinrich Holk was appointed governor . When Holk retired to seek reinforcements , he was succeeded by Scotsman Alexander Seaton . The imperial army renewed its assault on 26 and 27 May . When checked , Arnim resorted to bombardment awaiting Wallenstein ' s personal appearance . On 20 June , a Swedish auxiliary expedition , dispatched already on 2 June , arrived with 600 men from Norrland , commanded by colonel Rosladin . On 23 or 25 June , Stralsund concluded an alliance with Gustavus Adolphus of Sweden , scheduled to last twenty years . Gustavus Adolphus then stationed a garrison in the town , the first such on German soil in history . This event marked the starting point of Swedish engagement in the Thirty Years ' War . On 27 June , Wallenstein took command of the besieging forces , and renewed the assaults starting the very same night . The Scottish troops , entrusted with the defense of a crucial section of Stralsund ' s fortifications , distinguished themselves by an extremely fierce way of fighting . The main assault was on the eastern district of Franken , commanded by major Robert Monro . Of 900 Scots , 500 were killed and 300 wounded , including Monro . Rosladin was able to relieve Monro ' s force and re - take lost ground . An overall 2 , 000 defendants were killed and captured in this assault . Monro later recalled that " " we were not suffered to come off our posts for our ordinary recreation , nor yet to sleepe " " - for a period of six weeks . The following night , on 28 and 29 June , Wallenstein succeeded in taking the outer works of the fortifications . Rosladin was wounded and governor Seaton took over his command . On 29 June , Bogislaw XIV , Duke of Pomerania sent two of his high - ranking nobles , the count von Putbus and his chancellor von Horn , to persuade Stralsund to adhere to the Capitulation of Franzburg and surrender to Wallenstein . On 30 June , Rosladin persuaded the city not to enter into negotiations with Wallenstein , who had resorted to bombardment again . The same day , ten Swedish vessels re - inforced Stralsund with 600 troops , while under heavy fire by Wallenstein ' s forces . Soon after , Christian ordered another Scottish regiment , that of Alexander Lindsay , 2nd Lord Spynie , to help with the defence of the town . These troops arrived around 4 July and suffered huge casualties ( being reduced from a regiment to four companies ) in the ensuing assaults , many led by Wallenstein in person . On 10 July , Wallenstein and Stralsund negotiated a treaty in the " Hainholz " woods northwest of the town , requiring Stralsund to take in Pomeranian troops . The treaty was signed by Wallenstein and Bogislaw XIV on 21 July , but not by Stralsund . Though Bogislaw vouched for the town , the treaty did not come into effect . Already on 2 July , Stralsund had been reinforced by 400 Danish troops , and by 1 , 100 troops of the Danish - Scottish regiments of Donald Mackay and Alexander Lindsay , Lord Spynie in the following week . Another week later , Scotsman Alexander Leslie , serving Sweden , arrived with 800 Norrlanders and succeeded Seaton as Stralsund ' s governor . Leslie commanded a total of 4 , 000 to 5 , 000 troops . The Danish support amounted to 2 , 650 troops deployed during the siege . Heavy rainfall between 21 and 24 July turned the battlefield into a marsh . On 4 August , Wallenstein lifted the siege , acknowledging his first misfortune in the Thirty Years ' War . Aftermath . After the unsuccessful siege , Wallenstein headed to nearby Wolgast , to fight a final battle with Christian IV : Danish troops had landed in the area and occupied the island of Usedom , and had taken the town of Wolgast on 14 August without fighting . On 22 August , Wallenstein retook the town . Also in August , Swedish chancellor Axel Oxenstierna came to Stralsund , and offered negotiations to Wallenstein . The latter however refused . The inability to take Stralsund was to become one of the obstacles which led to Wallenstein ' s temporary dismissal in 1630 . When Gustavus Adolphus ' invaded Pomerania in June 1630 , he used his bridgehead in Stralsund to clear the flanks of his landing forces . Bogislaw XIV concluded an alliance with the Swedish king in the Treaty of Stettin in July . Wallenstein ' s forces were subsequently driven out of the Duchy of Pomerania , and Swedish forces had taken complete control of the duchy when Wallenstein ' s forces in Greifswald surrendered in June 1631 . During the Swedish campaign , Alexander Leslie was succeeded as the governor of Stralsund by another Scot in Swedish service , James MacDougal , in 1630 . From 1679 to 1697 , the position was to pass to yet another Scot , Peter Maclean . Part of Wallenstein ' s forces were infected with the Black Death . During the siege , the epidemics swept into the town , killing 2 , 000 in the months of August and September alone . The battle of Stralsund entered Pomeranian folklore . The population of Stralsund commemorates the siege of 1628 with an annual festival , " " Wallensteintage " " ( " Wallenstein Days " ) .