Poznań Fortress, known in German as Festung Posen (Polish: Twierdza Poznań) was a set of fortifications in the city of Poznań (German: Posen) in western Poland, built under Prussian rule in the 19th and early 20th centuries. It represents the third largest system of its kind in Europe.
The first set of fortifications was a tight defensive ring around central Poznań, including the main citadel called Fort Winiary (now the Cytadela park). Construction of these fortifications began in 1828. Later, beginning in 1876, an outer defensive ring was built around the perimeter of the city, consisting chiefly of a series of "forts", which mostly still survive.
The term Festung Posen was also used by the Nazi German occupiers during the Red Army's advance in the closing phases of the Second World War, to refer to Poznań's status as one of the "strongholds" (Festungen) which were to be defended at all costs. It fell in the Battle of Poznań (1945), with Fort Winiary the last point of resistance.
Initial planning Poznań (Posen) came under Prussian rule with the Second Partition of Poland in 1793. Its medieval city walls were obsolete by that time, and were mostly taken down in the early 19th century to facilitate the city's growth. The Prussian authorities first made plans to build new fortifications in December 1815.Biesiadka, Gawlak, Kucharski, Wojciechowski, p. 19 The city lay on the shortest route from the border with Congress Poland (and hence with the Russian Empire) to Berlin, and was also an important point on the route from West Prussia to Silesia; therefore, according to General Karl von Grolman, its fortification would show that Prussia had no intention of giving up those lands, and would defeat the "continuous intrigues and plotting" on the part of the Poles.Karl von Grolman's report of 22 May 1817 A preliminary plan sketched by Grolman on 9 July 1817 provided for fortification of Winiary Hill north of the city, as well as the area of St. Kazimierz's Church in Śródka to the east. Army engineers added to these plans a weir on the river Warta (Warthe), which would enable the river to be used as part of the defences.Biesiadka, Gawlak, Kucharski, Wojciechowski, p. 20
Building was planned to begin in 1817, but initially no funds were available for the work (due to the costs of fortifying Cologne and Koblenz). Planning continued, however: in 1823 Grolman proposed a line of defences surrounding the left-bank (main) portion of the city, with additional fortifications 500–1000 metres in front of the main line.
In 1827, Johann von Brese, then working in the War Ministry's engineering section, was instructed to prepare a detailed plan. The result, dated 23 March 1828, included the large fort on Winiary Hill, fortifications on the cathedral island (Ostrów Tumski) and the right bank, and the core defensive line surrounding the left-bank city. The plan was approved by General Gustav von Rauch (chief inspector of forts), and then presented by General Karl von Hake to King Frederick William III, who approved it in principle, asking Rauch to make some improvements.Biesiadka, Gawlak, Kucharski, Wojciechowski, p. 21 These were agreed on 18 June 1828 by a committee of officers headed by Rauch, and then supplemented by Rauch himself (it was due to Rauch that Grolman's proposed additional line in front of the main defences was excluded from the plans). The king gave his final approval on 14 August 1828, ordering Hake to begin construction with the Winiary fort and the weirs on the Warta and on the Wierzbak (Wierzbach) stream.
Construction of the inner fortifications
On 14 March 1828 Captain Moritz von Prittwitz und Gaffron, who had been a member of Rauch's committee, was appointed chief of construction of Festung Posen. In May, he and five subordinate officers began marking out the outline of the first fortifications – the defensive barracks of the Winiary fort (later the reduit). Building began on 23 June 1828 (the fort would be completed in 1839). Fortification also soon began north of Poznań Cathedral and in the south-western part of the main defensive line. Work was carried out by the 5th Pioneers Division, re-stationed from Glogau (Głogów). Following the Polish November Uprising against Russia in 1830, the unfinished fortifications were manned temporarily for defensive purposes.Biesiadka, Gawlak, Kucharski, Wojciechowski, p. 22
In 1829–1832 the Große Schleuse weir was built on the Warta. In October 1832 the main stream of the Warta was moved westwards, the former stream being closed off with an overfall weir (Große Überfall), connected to a seven-span defensive bridge. In 1832–1837 the Kleine Schleuse on the Wierzbak was built.Biesiadka, Gawlak, Kucharski, Wojciechowski, p. 23 The Dom Schleuse weir on the east side of Ostrów Tumski was built in 1834–1838, with the Dom Flesche lunette to the north. On 1 October 1834 Festung Posen was classified as a "Fortress Second Class", and completed parts of the fortifications were armed. Around 1837–1838 the Magazin Cavalier and Ziegel Flesche were built south of Fort Winiary.Biesiadka, Gawlak, Kucharski, Wojciechowski, p. 24 Work also proceeded on the right bank, where there were to be two forts connected by embankments. The northern embankment, containing Bydgoszcz Gate, was completed in 1839.
On 16 March 1839 the king ordered a renewal of work on the fortifications, which had been suspended. Brese produced working plans on 1 February 1840, and the king approved an annual budget of 300,000 thalers. Work began again in March 1840, under a new director, Reichel (replaced by Lange in the 1850s).Biesiadka, Gawlak, Kucharski, Wojciechowski, p. 25 Bastions III and V were first to be built. Work was interrupted in 1848 due to the Greater Poland Uprising and "Spring of Nations". Later Bastions IV, VI, II and I were constructed, and in 1860–1861 connecting roads were built, as well as a number of brick blockhouses. This completed the ring (enceinte) around the left-bank city. Each of the six bastions had a large caponier shielded by embankments connected to the cavaliers. There was also a separate caponier on Grobla (Graben) island, beyond the Graben Schleuse weir.Biesiadka, Gawlak, Kucharski, Wojciechowski, p. 26
Work also continued on the right bank, with the Reformaten Fort completed in 1842, and the Warsaw Gate in 1845, as well as the Cybina Cavalier, Cybina Schleuse, Cybina Flesche, and Fort Rochus (and adjacent embankments) to the south. The section containing the Kalisz Gate was last to be built.Biesiadka, Gawlak, Kucharski, Wojciechowski, p. 27
Around 1850 it was decided to make an independent fortress on Ostrów Tumski. Canals were built east and west of the island, partly for flood prevention (Vorfluth Canal I and II), completed by 1864. Defences were built in the second half of the 1850s: Dom Redoute at the southern end of the island, embankments on the east and west sides of the island, and Dom Lünette in the north-west. Around 1862 the moat of Dom Redoute was completed.
In 1864 the Poznań Fortress was declared completed and reclassified as a fortress "of the first class". King Wilhelm I issued a decree renaming many of the elements of the fortifications in honour of Prussian generals.
Later alterations to the central ring of fortifications mainly resulted from the introduction of new types of armaments and ammunition, and the building of railway and tram lines.Biesiadka, Gawlak, Kucharski, Wojciechowski, p. 31 In 1869–1872 the north-eastern fortifications were rebuilt to allow the building of a railway to Toruń (Thorn). Powder stores were built and strengthened; in 1873–1874 the embankments around powder stores were widened. In 1875–1877 wooden bridges were mostly replaced with steel, and the gates in the fortifications were also strengthened. Ritter Thor was built in 1881–1882 to improve access to the city's new rail station.
By the 1890s the outer ring of forts had been built around the perimeter of the city, and much of the inner ring began to be demolished (see below). However the main forts remained in use. In 1910 reinforcement work took place at Fort Winiary, Fort Steinäcker and Cavalier Aster.
Elements of the left-bank fortifications
The following were the main elements of the ring of fortifications on the left bank of the Warta (listed in anti-clockwise order): Fort Winiary. The main fort, lying north of the city as it was then, and popularly known as Poznań's citadel; converted after World War II into the Cytadela park. For details of its construction and history, see Poznań Citadel. Kleine Schleuse ("Little Lock"), a weir built in 1832–1837 on the Wierzbak (Wierzbach) stream which flowed eastwards towards the Warta (this part of the stream is now combined with the Bogdanka and flows in underground drainage pipes). The weir was connected to the western end of Fort Winiary's reduit to the north, and to Fort Adalbert (Hake) to the south. Fort Adalbert, renamed Fort Hake in 1864. Built in the 1830s on the north side of the hill containing St. Wojciech's (St. Adalbert's) church. Ziegel Flesche ("Brick Lunette", named for a brickworks on the Wierzbak), later Waldersee Flesche, a lunette situated somewhat west of the fortifications running south from Fort Adalbert, being connected to them by a long gorge. Built in the late 1830s. Magazin Cavalier, a fortified embankment between Fort Adalbert and Bastion VI, built 1837–1838. Bastion VI, renamed Bastion Waldersee in 1864. It stood close to the junction of today's Al. Niepodległości and ul. Solna; the western line of fortifications generally follows today's Al. Niepodległości and ul. Kościuszki. Between Bastion VI and Bastion V was Cavalier VI (Cavalier Bonin from 1864). Bastion V, renamed Bastion Tietzen in 1864, north of where the Zamek ("Imperial Castle") building now stands. Connected to Bastion IV by Cavalier V (Cavalier Stockhausen). To the west was an additional caponier close to the then railway station, now built in under the Rondo Kaponiera roundabout at the western end of Święty Marcin. Bastion IV, renamed Bastion Colomb in 1864. Stood partly on the site of the park on ul. Powstańców Wielkopolskich west of Al. Niepodległości. A blockhouse survives; it was excavated and restored in 1998, and now houses a pub. Between Bastion IV and Bastion III was Cavalier IV (Cavalier Strotha). Bastion III, renamed Bastion Grolman in 1864 and Reduta Przemysława after World War I. Connected to Bastion II by Cavalier III (Cavalier Rohr). It stood close to today's Plac Andersa. Bastions and Cavaliers I–III formed the southern edge of the fortifications, with a partial moat in front. Bastion II, renamed Bastion Brünneck in 1864. Connected to Bastion I by Cavalier II (Cavalier Witzleben). Bastion I, renamed Bastion Röder in 1864, close to the west bank of the Warta. Running east from it onto the then island of Grobla (Graben) was Cavalier I (Cavalier Boyen). Graben Schleuse or Grabendamm, within Cavalier I, an overfall weir on the branch of the river west of Grobla. It regulated the water level in that branch and in the moat of the southern fortifications.
Elements of the right-bank fortifications The following were the main elements of the fortifications on the right bank of the Warta: Fort Rochus, renamed Fort Rauch in 1864, and Fort św. Rocha (later Reduta Marcinkowskiego) after World War I. It guarded the southern end of the right-bank fortifications, close to today's St. Roch bridge. There was a caponier to the west of the fort, on the river bank. The gunneries survived the demolitions in the 1920s. Cybina Cavalier, renamed Cavalier Aster in 1864, on the south bank of the Cybina stream, near what is now the western end of Lake Malta. In 1869–1870 a powder store (no. 6) was built there, and in 1872 a powder laboratory. The cavalier was reinforced in 1910.