In response, Ferdinand II, Holy Roman Emperor, had Albrecht von Wallenstein raise an additional army to support Tilly.

[9] The remnants of Mansfeld's army left Central Germany, and turned to Silesia and Hungary to regroup with Gabriel Bethlen's forces.

[10] 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,[9] Tilly and Wallenstein were able to subsequently expel Christian IV from the North German plain, organized in the Lower Saxon and Upper Saxon imperial circles, and pressure him even in Danish Jutland.

[9] The internally divided Upper Saxon circle, to which the Duchy of Pomerania with Stralsund belonged, was incapable of self-defence and had formally declared neutrality.

Gustavus Adolphus of Sweden was since 1626 involved in the Polish-Swedish War, with Poland allied to the Holy Roman Empire.

[13] In this war, Scotsman Alexander Leslie started his career in Swedish service as commandant and governor of Pillau in East Prussia.

[13] Gustavus Adolphus had made plans to intervene in the Holy Roman Empire, of which the Riksdag commission approved in the winter of 1627/28.

[6] 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.

[6] The Capitulation of Franzburg required all towns except for ducal residences to take in imperial troops,[6] and Wallenstein had ordered Arnim to occupy the Pomeranian ports and seize their vessels already in October.

[15] Stralsund however was unwilling to give in,[16] as its status as a Hanseatic town had provided for considerable self-determination and independence from the Pomeranian dukes.

[22][23] When Holk retired to seek reinforcements, he was succeeded by Scotsman Lieutenant Colonel Alexander Seaton of Mackay's Regiment.

[20] The Scottish troops, entrusted with the defence of a crucial section of Stralsund's fortifications, distinguished themselves by an extremely fierce way of fighting.

[29] 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.

[31] By the 17 July Scotsman Alexander Leslie, arrived with 1,100 troops, including more Scottish volunteers, and succeeded Seaton as Stralsund's governor.

[25] One of Leslie's first actions was an audacious all-out assault on the besieging troops which Robert Monro described as follows: Sir Alexander Leslie being made governour, he resolved for the credit of his countrymen to make an out-fall upon the Enemy, and desirous to conferre the credit on his own Nation alone, being his first Essay in that Citie[34] Heavy rainfall between 21 and 24 July turned the battlefield into a marsh.