However the Russian Empire began an offensive in Eastern Prussia soon after the commencement of hostilities and the German army was forced to relocate substantial forces to the east. After crucial strategic mistakes by Russian generals at the Battle of Tannenberg and the First Battle of the Masurian Lakes, the Germans, after these victories, found themselves with a substantial number of captured Russian soldiers, around 137,000 prisoners. Without a prior plan to accommodate this many captives the Germans began hastily building the facilities to house them, most of which were located in Gdańsk Pomerania, including Tuchola.[2]