The Festung Posen (present day Poznań) fell on 23 February 1945 after resisting the siege for over a month.

Commander

Generalmajor Ernst Mattern (? - 28 January 1945)
Generalmajor Ernst Gonell (28 January 1945 - 23 February 1945)

Order of battle

Schule V für Fahnenjunker der Infanterie
Inf.Ers. und Ausb.Btl. 500
Fest.Inf.Btl. 1442
Fest.Inf.Btl. 1446
Fest.MG.Btl. 82
Fest.MG.Btl. 83
Fest.MG.Btl. 90
Volkssturm-Btl.
SS-Kampfgruppe Lenzer (SS-Obersturmbannführer Wlhelm Lenzer)

Sources used

Georg Tessin - Verbände und Truppen der deutschen Wehrmacht 1933-1945

Reference material on this unit

Günther Baumann - Posen '45: Bastion an der Warthe
Maciej Karalus & Michał Krzyżaniak - Poznán 1945
Jonny Neuwirth - Ein Fahnenjunker von Posen: Vae Victis!
Richard Siegert - Tiger of Posen: Memoirs of Panzer Man Richard Siegert at the Siege of Posen Eastern Front, January-February 1945