The 'Milau-Elbing Offensive Operation' was the Soviet second of the six sub-operations together constituting the 'East Prussian Strategic Offensive Operation', and was carried out by forces of the 2^nd Belorussian Front in order to isolate Heeresgruppe 'Mitte' from the rest of the German forces on the Eastern Front and to capture Elbing on the approaches to Danzig and Gdynia (14/26 January 1945).

The other sub-operations were the 'Insterburg-Königsberg Offensive Operation' (14/26 January), the 'Rastenburg-Heilsberg Offensive Operation' (27 January/12 February), the 'Braunsberg Offensive Operation' (13/22 March), the 'Königsberg Offensive Operation' (6/9 April) and the 'Samland Offensive Operation' (13/25 April).

By the beginning of the 'Milau-Elbing Offensive Operation', the troops of Marshal Sovetskogo Soyuza Konstantin K. Rokossovsky’s 2^nd Belorussian Front had occupied the line of the Augustow Canal, the Bobra river and the Nareva river, along which the Soviets had established bridgeheads at Augustow, Ruzhan and Serotsk. The main blow was to be delivered from the Ruzhan bridgehead by General Polkovnik Aleksandr V. Gorbatov’s 3^rd Army, General Leytenant Nikolai I. Gusev’s 48^th Army, General Polkovnik Ivan I. Fedyuninsky’s 2^nd Shock Army and General Polkovnik Vasili T. Volsky’s 5^th Guards Tank Army at Marienburg. General Polkovnik Pavel I. Batov’s 65^th Army and General Polkovnik Vasili S. Popov’s 70^th Army struck from the Serotsk bridgehead to the north-west. General Polkovnik Ivan T. Grishin’s 49^th Army attacked Myshinets.

Facing these Soviet thrusts were modernised and well-equipped field fortifications and anti-tank barriers, many of them dating from the period before the start of World War II. The Germans thus held three defensive lines, two of them having pillbox-strengthened strongpoints at the rate of four pillboxes per 0.62 miles (1 km). Field-type positions had between three and five lines of trenches. Old fortresses, such as those at Mlawa, Modlin, Elbing, Marienburg and Toruń, were incorporated into the defences and added further strength. The combination of the terrain and the man-made German defences made it very unlikely that the Soviets would be able to effect any breakthrough in just a single area, so the Soviets planned and executed several breakthrough undertakings at intervals of between 3.1 and 13 miles (5 and 21 km). In the assault sectors the Soviets massed high densities of artillery, in the order of between 180 and 300 guns per (0.61 mile (1 km) of front. As the time for their offensive approached, the Soviets undertook a programme of continuous land and air reconnaissance to assess and then reassess the nature of the German defences.

It was on 14 January that Soviet troops launched their offensive against Generaloberst Walter Weiss’s 2^nd Army. The Germans put up stubborn resistance and made a number of counterattacks. But the combined arms armies, supported by two tank and mechanised corps, broke through the main defence line on the following day, and by the end of 16 January had advanced between 6.1 and 15.5 miles (10 and 25 km), and completed the breakthrough of the Germans' entire tactical defence area. By 16 January a major improvement in the weather made it possible for Soviet air units to operate more actively, these units flying more than 2,500 sorties per day. On 17 January, the 5^th Guards Tank Army entered the breakthrough crested by the 48^th Army, and during this day the tank army increased the depth of the breakthrough to some 37 miles (60 km) and reached the Milau fortified area.

In the early days of the Soviet offensive, up to 85% of the front’s aviation forces were involved to facilitate a successful offensive by the tank army, and several concentrated air attacks were delivered against the railway junctions at Ortelsburg, Allenstein and Naidenburg. The concentration of the Soviet air strength in support of the 2^nd Belorussian Front’s right flank made it possible to disrupt any attempts to effect a regrouping of the German forces, and to provide effective support for the tank army. The speed of the Soviet tank offensive also thwarted the German plan for a counterattack, which was being readied for launch from the area of Ciechanów and Pshasnysh.

Developing their offensive, Soviet troops from the north and south bypassed the Mlava fortified area and by the morning of 19 January had captured Mlava. By this time, the forces on the front’s left wing had reached the approaches to Plonsk and captured Modlin. The main forces and reserves of the 2^nd Army were destroyed. On the morning of 19 January, the troops of front’s centre and left wing, with powerful air support, began a pursuit of what was left of the 2^nd Army. On 22 January, under threat of the imminent encirclement of their surviving forces, the German high command began to pull troops back to the north-west from the area of the Masurian Lakes. However, by 25 January, the Soviet mobile formation had bypassed Elbing from the east, reached the Frisches Haff bay and cut the main overland lines of communication on which Heeresgruppe 'Nord' relied for the maintenance of its capabilities. The Germans could from this time onward communicate with their troops operating beyond the Vistula river only along the Frische-Nerung spit in the Bay of Danzig. On 26 January, elements of the 2^nd Shock Army entered Marienburg, and by this same time the forces of the Soviet front’s left wing had reached the Vistula river and in the Bromberg (Bydgoszcz in Polish) region had seized a bridgehead on this waterway’s western bank.

During the offensive, the Soviet forces had decisively defeated the entire 2^nd Army and part of General Friedrich Hossbach’s 4^th Army. East Prussia and the German forces attempting to hold it were now cut off from the rest of Germany. The Bromberg bridgehead also created the conditions for an offensive deep into eastern Pomerania.

One of the major results of the 'Insterburg-Königsberg Offensive Operation and 'Milau-Elbing Offensive Operation' was the creation of the Heiligenbeil pocket, which became the site of a major encirclement battle during the closing weeks of World War II. In this pocket, located between Braunsberg and Heiligenbeil (now Mamonovo), and which lasted from 26 January and 29 March 1945, the remnants of Hossbach’s (from 29 January General Friedrich-Wilhelm Müller’s) 4^th Army were almost wholly destroyed during the Soviet 'Braunsberg Offensive Operation' (13/22 March).

The Soviet 'East Prussian Strategic Offensive Operation' had started on 13 January with the object of rolling up the substantial German defences in East Prussia and cutting off the provincial capital of Königsberg. The Soviet forces were opposed by Generaloberst Georg-Hans Reinhardt’s Heeresgruppe 'Mitte', which included the 4^th Army. While the 3^rd Belorussian Front initially met strong resistance, the outnumbered German forces soon began to suffer serious ammunition shortages. Reinhardt warned of the serious nature of the situation in this as early as 19 January, but was not permitted to make a phased withdrawal.

To save his formations and units from encirclement by the Soviet offensive, Hossbach started to pull the 4^th Army back to the west in direct contravention of orders, abandoning the prepared defences around Lötzen on 23 January. By this time, Rokossovsky’s 2^nd Belorussian Front had already broken through on Hossbach’s right, and the 5^th Guards Tank Army advanced toward the coast of the Baltic Sea, thereby cutting off most of East Prussia. Through a series of forced marches in atrocious winter weather, and accompanied by thousands of civilians, the 4^th Army moved to the south-west in the direction of Elbing, which was still in the hands of the 2^nd Army, but found its path blocked by Soviet forces of the 48^th Army in the area to the east of the town.

An attack beginning on the night of 26/27 January initially resulted in leading elements of Generalmajor Ernst König’s 28^th Jägerdivision breaking through to Elbing, where they linked with Generalleutnant Dr Karl Mauss’s 7^th Panzerdivision. Other German formations were driven back during the next four days, however, after the 48^th Army had regrouped. Hossbach’s forces now found themselves pushed into a Kessel ('cauldron' or pocket) with their backs to the waters of the Frisches Haff.

The Soviet formations involved in completing the creation of the Kessel within Rokossovsky’s 2^nd Belorussian Front included the 5^th Guards Tank Army, 48^th Army, 3^rd Army and 50^th Army, and within Vasilevsky’s 3^rd Belorussian Front the 31^st Army, 28^th Army and 1^st Air Army. Facing these Soviet forces were the 4^th Army's VI Corps under General Horst Grossmann (102^nd Division, 24^th Panzerdivision and 349^th Volksgrenadierdivision); XX Corps under General Rudolf Freiherr von Roman (131^st Division, 61^st Volksgrenadierdivision, 21^st Division, 14^th Division, 292^nd Division and 56^th Division); and XLI Panzerkorps under General Helmuth Weidling (170^th Division, Fallschirm-Panzergrenadierdivision 2 'Hermann Göring', Panzergrenadierdivision 'Grossdeutschland', 28^th Jägerdivision, 562^nd Volksgrenadierdivision and 50^th Division). As was typical of all German military forces at this late stage of World War II, all of these formations were considerably below strength even at the start of the 'East Prussian Offensive Operation'. Moreover a number of formations, such as the 299^th Division and 18^th Panzergrenadierdivision were destroyed, disbanded or completely evacuated before the collapse of the Kessel.

Hossbach was relieved of command on 29 January and replaced by Müller,whose three corps were ordered to end their break-out attempt on the following dat. Along with some units of the 2^nd Army, they found themselves encircled in the area of Heiligenbeil and Braunsberg. Many of the civilians trapped with them attempted to escape across the frozen Frisches Haff to the Frische Nehrung and thence to Pillau or Danzig after reinforced paths marked by lamps had been constructed across the ice by the 4^th Army's engineers.

The German political leadership had effectively forbidden the evacuation of East Prussia’s civil population but, regardless of this fact, when the Soviets attacked on 12 January civilians began a mass flight west to the coast of the Baltic Sea. Many were killed by Soviet troops, and by extreme cold. On the coast, in particular in the harbour of Pillau, the German navy managed to evacuate tens of thousands of civilians, and encouraged fierce resistance on land, since every delay to the Soviet progress meant the rescue of additional old people, women and children.

Soviet attempts to break through the German perimeter early in February were fought off, and in this effort the 4^th Army benefitted from heavy gunfire support from the German heavy cruisers Admiral Scheer and Lützow firing across the Haff from the Baltic Sea into the Frauenburg end of the pocket. Frauenburg itself fell to the Soviets on 9 February in fierce fighting involving elements of Generalleutnant Siegfried Hass’s 170^th Division. During one Soviet attack Chernyakhovsky, the 3^rd Belorussian Front’s commander, was killed by a shell splinter near Mehlsack. His successor, Marshal Sovetskogo Soyuza Aleksandr M. Vasilevsky, having effectively contained the remains of the German army group, concentrated on assembling reinforcements over the next month. Under the supervision of Generalmajor Karl Henke, the Germans continued to attempt resupply and evacuations of wounded along the Frische Nehrung, often at night to avoid air attack. A long, narrow corridor to the besieged garrison of Königsberg was also maintained against the attacks of the 11^th Guards Army through a joint effort by the garrison and Generalmajor Karl Lorenz’s Panzergrenadierdivision 'Grossdeutschland'.

Despite the fact that they had no realistic hope of victory, and were severely short of men, ammunition and fuel, the German forces in East Prussia continued to offer strong resistance, inflicting extremely high casualties on the Soviet forces during the 'East Prussian Strategic Offensive Operation'. Extemporised Kampfgruppen were often bolstered by members of the civilian population press-ganged into the Volkssturm, and many of East Prussia’s towns and villages had been turned into fortified strongpoints to supplement the substantial fortifications centred on Heiligenbeil. The fighting was prolonged as long as possible by the Germans in order to keep open the escape routes for civilians, and because requests to evacuate the main body of the 4^th Army were steadily refused by the German high command.

The Soviet attack, however, came tragically late for the remaining inmates of the Heiligenbeil concentration camp, along with other camps in the area. Even as Hossbach’s forces were attempting to break out of East Prussia, the prisoners were driven to the coast and forced into the frigid water of the Baltic Sea to drown or freeze.

The German pocket was finally crushed in an operation lasting from 13 to 29 March, officially known as the 'Braunsberg Offensive Operation', in preparation for the Soviet forces' final assault on Königsberg,

In this undertaking, the Soviet forces quickly cut communication between the Kessel and Königsberg by advancing to reach the coast about 5 miles (8 km) from the city on 15 March. The Soviet forces crossed the Frisching river in an attack on the night of 17/18 March, further rolling up the German defences of the Kessel from the east. The arrival of better weather from 18 March allowed the Soviet air forces to undertake an intense bombardment of the 4^th Army's positions.

With most of their communications cut, the German forces left in the pocket were now faced with the option of death or being taken prisoner. Some of the better formations, such as Generalmajor Erich Walther’s Fallschirm-Panzergrenadierdivision 2 'Hermann Göring' and Generalmajor Gustav-Adolf von Nostitz-Wallwitz’s 24^th Panzerdivision, were evacuated by sea, but most of the other German formations and units were gradually cut off in a series of small pockets on the coast Prisoner of war accounts suggest that many German units were now seriously understrength: Generalmajor Georg Haus’s 50^th Division, for example, was able to field only one incomplete regiment.

The Soviets finally took Braunsberg on 20 March. Heiligenbeil and its small port at Rosenberg, were attacked with incendiary bombs on 22 March and successfully stormed on 25 March, Heiligenbeil suffering almost complete destruction. Rosenberg was taken on 26 March, when the remnants of the 4^th Army fell back to the Kahlholzer Haken peninsula, where the perimeter was defended by elements of General Georg Jauer’s Panzerkorps 'Grossdeutschland' and König’s (from 12 April Oberst Hans Tempelhoff’s) 28^th Jägerdivision. The last evacuations took place on the morning of 29 March from Kahlholz and Balga, where a remnant of Oberst Helmuth Hufenbach’s 562^nd Volksgrenadierdivision was destroyed as it ought as the German rearguard: Hufenbach was posthumously promoted to Generalmajor.

Soviet sources claimed that their forces had killed 93,000 Germans and taken prisoner another 46,448 Germans in the course of the operation; German sources claim that many troops were evacuated from the Kessel to the Frische Nehrung. Given the chaos prevailing at this stage of the war, it is unlikely that accurate figures will ever be determined, many soldiers having simply disappeared.

Other elements of the 4^th Army continued to resist in the area round Pillau, and latterly on the Frische Nehrung, until May and the final surrender of Germany.