Toruń Fortress (, ) is a historic fortress located in Toruń, Poland, one of the largest fortresses in Central and Eastern Europe. It was built in 1872–1894 by the Kingdom of Prussia, when the city was part of the Prussian Partition of Poland. The fortress complex – a chain of forts surrounding the city, as well as numerous smaller fortifications supplementing it – was intended to defend the eastern border of Prussia (with the Russian Empire). Despite much planning and investment, the fortress did not play a significant role in the First World War nor in any later conflict. During the German occupation of Poland in the Second World War, Germany established and operated a prison for Poles and the Stalag XX-A prisoner-of-war camp for Polish, British, French, Australian and Soviet POWs in the fortress. It was the site of German massacres of Poles committed as part of the Intelligenzaktion. History Toruń was an important city, which following the Partitions of Poland was located just north and west of the border between Prussia and Russia, which runs from southwest to northeast, in the north along the Drwęca tributary of the Vistula River which passes through Thorn. With improvements in artillery techniques, including the introduction of rifled barrels and smokeless powder), the old medieval city walls, dating from the 13th-15th centuries, and bastion fortifications from the 17th century, even if modernized at the beginning of the 19th century, no longer provided sufficient protection for the town. The Prussian government started the construction of fortifications in 1872, at first using French prisoners of war taken during the Franco-Prussian War. The goal was to build a chain of forts surrounding the city of Toruń. The initial plans called for five main forts and two medium ones to be constructed. In the period of 1877–1884, forts II and XI were constructed, followed by forts IV, V, VII, XV, XIII and IX. Continuing changes in artillery and siege techniques, especially the introduction of an anti-building shell in 1883, rendered some of the plans for the fortress obsolete even before it was finished. For that reason, the importance of the main artillery forts was lessened in favor of infantry forts; some artillery forts were redesigned into infantry forts and more small fortifications were constructed. Over time the number of objects to be built increased. In the years 1888–1893, forts III, VI, VIII, X, XII and XIV