Russian forces under Friedrich Wilhelm von Buxhoeveden laid siege to Sveaborg after the fall of Helsingfors on March 2, 1808. However the Russian force which had captured Helsingfors consisted only of roughly 2 000 men who had no chances in even just harassing the fortress. It took well into mid March before Russians had concentrated 4 000 men to area under General Jan Pieter van Suchtelen who started more effective sieging of Sveaborg by building first artillery batteries for the siege artillery in its vicinity. By early April Russians had amassed 6 500 men and 59 artillery pieces, some of which had been taken from Svartholm fortress after it surrendered, to besiege Sveaborg.