This was the Soviet strategic offensive 1 into Pomerania and West Prussia (24 February/4 April 1945).
Marshal Sovetskogo Soyuza Konstantin K. Rokossovsky’s 2nd Belorussian Front had initially been tasked with advancing to the west in the area to the north of the Vistula river toward Pomerania and the major port city of Danzig, with the primary objective of protecting the right flank of Marshal Sovetskogo Soyuza Georgi K. Zhukov’s 1st Belorussian Front, which was pushing directly to the west in the direction of Berlin. During the 'East Prussian Offensive Operation', however, Rokossovsky was ordered to wheel directly to the north in the direction of Elbing, and this left substantial German forces intact in Pomerania, where they threatened the right flank of Zhukov’s front.
As a result, once the initial phase of the 'East Prussian Offensive Operation' had been completed, the 2nd Belorussian Front was redeployed with the intention of advancing to the north into Pomerania, eliminating the possibility of a German counter-offensive. Similarly, the parallel Silesian offensives of Marshal Sovetskogo Soyuza Ivan S. Konev’s 1st Ukrainian Front in the south were in part designed to protect the 1st Belorussian Front’s left flank.
The need to secure the flanks of the primary thrust delayed to April the Soviets' final push toward Berlin, which had originally been planned for February. Iosif Stalin’s decision to delay this push has been a subject of some controversy among both the Soviet generals and military historians, with one side arguing that the Soviets had a chance of securing Berlin much more quickly and with considerably fewer casualties during February, and the other arguing that the danger of leaving large German formations on the flanks could have resulted in a successful German counter-offensive and prolonged the war: the Germans did in fact mount a surprise counterattack in Pomerania in mid-February as 'Sonnenwende'.
However, the delay did have the advantage of opening the way for the Soviet forces to occupy significant parts of Austria in the 'Vienna Offensive Operation'.
As early as 13 February the German intelligence services had deduced that the Soviets would seek to clear Pomerania before advancing on Berlin. Generaloberst Walter Weiss asked permission to pull back his 2nd Army (a major formation within Reichsführer-SS Heinrich Himmler’s Heeresgruppe 'Weichsel' and, from 11 March Weiss’s Heeresgruppe 'Nord'), which was entrusted with the protection of a large and exposed sector running through Pomerania east toward the edge of East Prussia at Elbing, but almost inevitably all such authorisation was denied by Adolf Hitler.
Graudenz, on the Vistula river, was surrounded on 18 February and the garrison, in the form of Generalleutnant Heun’s 83rd Division, surrendered during the following month.
In overall terms, the new Soviet offensive fell on formations of Heeresgruppe 'Weichsel' including Weiss’s 2nd Army (General Martin Gareis’s XLVI Panzerkorps, General Mortimer von Kessel’s VII Panzerkorps, General Maximilian Felzmann’s XXVII Corps, General Walter Melzer’s XXIII Corps, General Friedrich Hochbaum’s XVIII Gebirgskorps and the fortress garrisons of Graudenz and Danzig), and also on the eastern flank of General Erhard Raus’s reconstituted 3rd Panzerarmee (Generalleutnant Martin Unrein’s III [germanisch] SS Panzerkorps and Generalleutnant Günther Krappe’s X SS Corps).
All of the the 2nd Army's corps were drastically below strength, and the army did possess was formations which were composed largely of fragmentary or extemporised formations and units. The 3rd Panzerarmee had been rebuilt using the corps of SS-Obergruppenführer und General der Waffen-SS Felix Steiner’s 11th SS Panzerarmee, only recently established but largely destroyed in Lithuania and East Prussia, where its remnants were now defending Königsberg.
The Soviet forces comprised the 2nd Belorussian Front and the right wing of the 1st Belorussian Front (General Major N P. Simoniak’s [from March General Polkovnik Fyedor I. Kuznetsov’s] 3rd Shock Army, General Polkovnik Mikhail Ye. Katukov’s 1st Guards Tank Army and General Polkovnik Semyon I. Bogdanov’s 2nd Guards Tank Army).
Rokossovsky started his offensive on 24 February using the fresh troops of General Leytenant Georgi K. Kozlov’s 19th Army, but after an initial advance of some 12.5 miles (20 km) these were brought to a halt by stubborn German resistance. On 26 February Rokossovsky inserted General Major Mikhail A. Gramagin’s III Guards Tank Corps in the area to the east of Neustettin, where it achieved a penetration of 25 miles (40 km), and replaced Kozlov by General Leytenant Vladimir Z. Romanovsky. The III Guards Tank Corps broke through at Baldenburg, while Neustettin on the front’s left flank fell to General Leytenant Nikolai S. Oslikovsky’s III Guards Cavalry Corps on 27 February.
Weiss had hurriedly assembled the VII Panzerkorps, including the remnants of Generalleutnant Dr Karl Mauss’s 7th Panzerdivision, at Rummelsburg to threaten the flank of the 19th Army. However, after a Soviet breakthrough at Koslin on 2 March, the 2nd Army found itself completely cut off from the rest of Heeresgruppe 'Weichsel'.
Zhukov’s right wing, a grouping of the 3rd Shock Army and the 1st and 2nd Guards Tank Armies, went over to the offensive on 1 March, attacking to the north with its major strength concentrated at Reetz. The entire eastern part of the 3rd Panzerarmee was cut off by their breakthrough after Generaloberst Heinz Guderian, the Oberkommando des Heeres chief-of-staff, had refused Raus’s request for permission to withdraw.
The western part of the 3rd Panzerarmee then pulled back toward Stettin near the mouth of the Oder river.
On 4 March Soviet tank units reached the Baltic Sea, and the German forces in Pomerania were trapped in a series of encirclements. The 2nd Army began to fall back on the Danzig fortified area, while the X SS Corps of the 3rd Panzerarmee was surrounded at Dramburg.
Rokossovsky launched the second phase of his offensive on 6 March. General Polkovnik Ivan I. Fedyuninsky’s 2nd Shock Army threatened to cut off the defending forces in the fortress of Marienburg, which was evacuated two days later, while in the east Elbing finally fell on 10 March.
Having warned that the Elbing pocket could not be held, Weiss was relieved of command on 9 March and replaced by General Dietrich von Saucken. The troops of the 2nd Army withdrew in disarray into Danzig and Gotenhafen, where the 2nd Belorussian Front laid siege to them.
Meanwhile Zhukov’s forces cleared the remnants of the 3rd Panzerarmee from the eastern bank of the lower Oder river, driving the Germans from their last positions in a bridgehead at Altdamm. Many civilian refugees from Pomerania had fled into the coastal port and city of Kolberg, which had been surrounded by 4 March.
In November 1944 Kolberg had been designated as a stronghold, the Festung 'Kolberg'. It was one of the key German positions in the 'Pomeranian Wall', a vital link between Pomerania and Prussia. The German high command planned to use the port to supply nearby German forces, and hoped that the threat of this stronghold would draw Soviet forces from the main westward thrust toward Berlin. The 'East Pomeranian Strategic Offensive Operation' managed to cut off and surround the city and thus the defenders of Festung 'Kolberg', whose commander was an elderly general who, as a result of illness, was transferred in February to a less demanding post. The new commander was Oberst Gerhard Troschel succeeded, from 1 March, by Oberst Fritz Fullriede.
The German defence forces represented various formations from Heeresgruppe 'Weichsel', some of them entrusted with the defence of the fortress, and others simply formations and units which had become isolated in the Kolberg pocket. The most notable units included elements of the 3rd Panzerarmee, SS-Brigadeführer und Generalmajor der Waffen-SS Dr Gustav Krukenberg’s 33rd Grenadierdivision 'Charlemagne' (französisch Nr 1), actually commanded by SS-Oberführer Edgar Puaud, and SS-Standartenführer Nikolaus Heilmann’s 15th Grenadierdivision (lettisch Nr 1). Estimates of the strength of the German defence, including local militiamen and volunteers, range from 8,000 to 15,000, supported by some 60 pieces of artillery, an armoured train, about 18 tanks and some 12 support vehicles of various types. The German units also received some air and sea support (including the 280-mm (11-in) guns of the heavy cruisers Lützow [ex-Deutschland] and Admiral Scheer, which had been classified as pocket battleships at the start of their careers.
The Soviet forces attacking the city can be divided into two waves: the first of Soviet formations (4/7 March) and the second of Soviet-controlled Polish formations (8/14 March 8), although some Soviet units took part in the fighting after 8 March. The primary Soviet units and formations were the 45th Tank Brigade (4/7 March) and the 272nd Division (6/9 March), and the Polish formations were elements of General Major Stanisław Popławski’s Polish 1st Army of the 1st Belorussian Front: the Polish 6th Division (from 7 March), Polish 3rd Division (from 9 March), Polish 4th Division (from 12 March) and various support units. More than 28,000 Polish troops were committed to the operation.
The first attack was led on 4 March by the Soviet units of the 1st Belorussian Front and 2nd Belorussian Front. The first Soviet units entered the city around 08.00, but were then driven back. On the same day, the nearby city of Köslin fell, and Soviets were therefore able to redeploy formations to boost their strength for the attempt to take Kolberg.
On 6 March the Soviet high command decided to turn the siege of the city over to its communist Polish allies. The Polish 1st Army was now tasked with the capture of the city, but its first attack was also repulsed. The German forces held stubbornly to the city, protecting the ongoing evacuation. As the garrison lacked anti-tank weapons, the German heavy cruisers lying offshore used their guns to support the defence. On 12 March the Polish 1st Army undertook a fresh assault, supported by heavy tanks, additional artillery units and the Polish 4th Division. The attack made progress, but only at the cost of very heavy casualties, and was broken off on 14 March. The Germans refused a Soviet demand to surrender.
On 15 March the fighting resumed and the Germans received reinforcements from Swinemünde, but these failed to stop the Polish forces. These latter took the barracks, part of the railway station and the Salt island. By 16 March the Germans had pulled back most of their forces and concentrated on the defence of the port. The destruction of the collegiate church after heavy artillery shelling by Katyusha unguided artillery rockets allowed the Polish troops to open the way into the inner city. The Polish forces assaulted the railway station, which was defended by an armoured train destroyed on 16 March, the pharmaceutical factory and the horse riding arena.
On 17 March the Germans abandoned most of their defence lines, leaving only a small number of troops to cover their retreat, and started to evacuate their main body of forces from the city. The Polish forces finally took the railway station and reached the port, but most of the German troops had been evacuated to Swinemünde.
More than 80% of the city was destroyed in the heavy fighting, and the Polish casualties were about 1,000 dead and 3,000 wounded.
As the Soviet forces approached Kolberg in February 1945, much valuable equipment, most of the inhabitants, some 70,000 refugees from surrounding areas and 40,000 German troops had been evacuated from the city, threatened by imminent siege, by German naval forces in 'Hannibal'. Only about 2,000 soldiers were left on 17 March to cover the sailing of the last transport vessels.
The Festerplatz 'Danzigtenhafen', also the main port for refugees from East Prussia escaping west, was defended as long as possible by von Saucken in order to keep open evacuation routes.
Rokossovsky opened his final offensive on 15 March. The main thrust, directed toward the coast at Zoppot between Gotenhafen and Danzig, was undertaken by General Leytenant Feofan A. Parkhomenko’s 70th Army and General Leytenant Ivan T. Grishin’s 49th Army advancing in parallel. The fighting was savage, but by 19 March the Soviet spearheads had reached the heights above Zoppot, while Generalleutnant Clemens Betzel’s (from 27 March Oberst Ernst-Wilhelm Hoffmann’s) 4th Panzerdivision had been pushed back to the outskirts of Danzig itself.
By 22 March the 70th Army had reached the sea, splitting the German defence. Gotenhafen was taken on 26 March, its defenders and many civilians retreating to the headland at Oxhoft, from where they were evacuated to the Hel peninsula. Danzig finally fell on 28 March, after which the remnants of 2nd Army withdrew to the delta of the Vistula river in the area to the north-east of the city. Evacuation of civilians and military personnel from there and from the Hel peninsula continued until the end of hostilities.