The 'Königsberg Offensive Operation' was the Soviet capture of Königsberg in the closing stages of the 'East Prussian Strategic Offensive Operation' (late January/9 April 1945).

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

General Ivan D. Chernyakhovsky’s 3^rd Belorussian Front captured Königsberg after a siege which started late in January 1945, when the Soviets initially surrounded the city. There followed heavy fighting for the overland connection between Königsberg and the port of Pillau, on a narrow peninsula to the south-west, but by March 1945 Königsberg lay far behind the main front line. The battle ended when the German garrison surrendered on 9 April after a three-day final assault.

The 'East Prussian Strategic Offensive Operation' was planned by the Stavka to prevent attacks on the northern flank of the Soviet armies pushing forward toward Berlin. This was a real threat as the Germans had very large forces in East Prussia, and during initial Stavka planning Iosif Stalin allocated to Marshal Sovetskogo Soyuza Konstantin K. Rokossovsky’s 2^nd Belorussian Front the task of destroying the German forces trapped there by the Soviet westward advance into Poland.

On 13 January 1945, some 1.5 million troops, supported by several thousands of tanks and large numbers of warplanes, of the 3^rd Belorussian Front 1 entered East Prussia, in which the Germans had created a huge network of fortifications, defensive lines and minefields. The offensive was initially almost a failure, the Soviet forces managing an advance of only 0.9 mile (1.5 km) on the first day through only the outermost three defence lines. In five days, and at the cost of very heavy losses, the Soviet forces managed to push forward only 12.5 miles (20 km), and had still not broken through the German defence lines into open country.

After overcoming their initial difficulties, however, the Soviets forces were able to start accelerating their advance, and on 24 January reached the coast of the Vistula Lagoon just to the north-east of Elbing near its south-western end. This cut off the German forces in East Prussia from all land communication with the rest of Germany, forcing the Germans to supply their surrounded forces by sea.

On 25 January Adolf Hitler tacitly acknowledged the current situation by renaming the three army groups operating in this area: Generalfeldmarschall Ferdinand Schörner’s Heeresgruppe 'Nord' became Generaloberst Heinrich-Gottfried von Vietinghoff-Scheel’s Heeresgruppe 'Kurland', Generaloberst Georg-Hans Reinhardt’s Heeresgruppe 'Mitte' trapped in East Prussia became Generaloberst Dr Lothar Rendulic’s Heeresgruppe 'Nord', and Generaloberst Josef Harpe’s Heeresgruppe 'A' became Schörner’s Heeresgruppe 'Mitte'.

Heeresgruppe 'Nord' was squeezed still farther by a succession of Soviet attacks and was divided into three pockets: one around Königsberg, one on the adjacent Samland peninsula, and one on the coast of the Frisches Haff in the south-west (the Heiligenbeil pocket).

By a time late in January the 3^rd Belorussian Front had surrounded Königsberg on the landward side, severing the road down the Samland peninsula to the port of Pillau, and trapping Generaloberst Erhard Raus’s 3^rd Panzerarmee and some 200,000 civilians in the city. The options open to the civilian population in the poorly provisioned city of Königsberg were to stay in the city and starve, or to cross the front line to the dubious mercy of the Soviet forces, or to cross the ice of the Frisches Haff to Pillau in hope of finding a place on an evacuation ship. Hundreds chose to cross the front line, but about 2,000 women and children per day chose to cross the ice on foot to Pillau. Returning from a visit to Berlin, Erich Koch, the Gauleiter of East Prussia, chose to stay in the relative safety of Pillau to organise the evacuation rather than return to Königsberg. The first evacuation steamer from Pillau carrying 1,800 civilians and 1,200 casualties reached safety on 29 January.

Throughout February there was bitter fighting as the Germans tried to maintain the narrow connection between Königsberg and Samland, and for a time the Soviet forces severed this connection and completely cut off the city. However, on 19 February the 3^rd Panzerarmee and General Friedrich-Wilhelm Müller’s 4^th Army, attacking from the direction of Pillau, managed to force open a corridor from Königsberg to Pillau. Led by a captured T-34 tank, this attack was spearheaded by Generalmajor Henning von Thadden’s 1^st Division from Königsberg, and was tasked with the establishment of a land link with General Hans Gollnick’s XXVIII Corps, which held parts of the Samland peninsula, including the vital port of Pillau. Capturing the town of Metgethen, the unit opened the way for Generalmajor Günther Hoffmann-Schönborn’s 5^th Panzerdivision to join with Gollnick’s forces near the town of Gross Heydekrug on the following day. This action stabilised the German defence until April as it reopened the land route between Königsberg and Pillau along which supplies could be delivered by ship, and the wounded and refugees evacuated.

In March the situation stabilised as by this time the main front had moved considerably farther to the west, and the Soviets now allocated only a low priority to the capture of Königsberg. Even so, the garrison was intact and showed no signs of surrender, so eventually the Stavka decided that the city should be taken by direct assault rather than protracted siege.

The task of planning an assault on Königsberg was not easy. In the city were five full-strength divisions and supporting elements, totalling 130,000 men, together with strong defensive positions dating from the late 19^th century and including 15 forts interconnected by tunnels and designed to withstand the bombardment of heavy artillery. The Germans still held a narrow land connection to their pocket on the Samland peninsula, and the capture of the city required that this link, defended with huge tenacity, be severed.

The German troops on the peninsula comprised Gollnick’s Armeeabteilung 'Samland', which was based on the commander’s own XXVIII Corps, and this could be expected to counterattack to prevent this from happening.

Königsberg was surrounded by three concentric rings of fortifications: an outer ring reinforced by 12 forts outside the town, a middle ring in the outskirts, and the inner city which was a single fortress of anti-tank defences, barricades and land mines, together with a number of other forts.

The Soviet commanders planned to rely strongly on air and artillery support, the density of the Soviet artillery concentration reaching some 400 pieces per mile (250 pieces per km) in some areas. After a four-day preparatory artillery bombardment, the Soviet assault started on 6 April. This assault was planned as a number of concentric attacks from several points around the perimeter designed to meet in the centre: this would divide the city’s defenders into isolated groups which would not be able to provide each other with mutual support.

There were two main assault areas: in the north-west were the 39^th Army and 43^rd Army with, from west to east, the LXIV Corps, VI Guards Corps, CXIII Corps, XC Corps, XIII Guards Corps, LIV Corps and CXXIV Corps, and in the south the 11^th Guards Army with the XXXVI Guards Corps, XVI Guards Corps and VIII Guards Corps. The 50^th Army was stationed in the north-eastern part of the front, but played only a limited part in the operation.

In the southern part of the front, the operation started at dawn on 6 April with an intense artillery bombardment and heavy bombing, lasting three hours, followed by the first attack. The Soviet infantry divisions quickly penetrated through the first defence line as its defenders had for the most part been killed or incapacitated by the severe bombardment, and the remainder were demoralised. The leading regiments had reached the second line by 12.00, when their progress was halted by stronger opposition, so forcing the Soviet commanders to commit their reserve forces. Three hours later, the second line had been overrun in several places.

The main assault was that in the north, and this began at the same time. By 12.00 the first defence line had fallen and the second line had been badly shaken and broken in several places. However, in the afternoon, the Soviet advance became increasingly slow, especially on the right flank, as the Armeeabteilung 'Samland' on the western outskirts of the city delivered several flank attacks. The battle came to a temporary halt at dusk, allowing both sides to consolidate their lines, regroup their forces and bring up reserves. This first day had gained mixed results, for the Soviet progress had not been as rapid as expected, but both city’s defences and the defenders' morale had been seriously shaken: troops, including officers, began to surrender periodically. During this first day of assault, bad weather prevented the Soviet troops from using precision bombing with as much effect as they would have liked.

During the night the German troops attempted several counterattacks, using their last reserves, but all of these were driven off. The worst part of the front was still the one facing the Armeeabteilung 'Samland', where a dozen such counterattacks were attempted.

The arrival of better weather conditions on 7 April allowed the Soviets to make use of daylight precision bombing. Several hundred bombers of the 1^st, 3^rd and 15^th Air Armies, supported by the aviation arm of Vitse Admiral Vladimir F. Tributs’s Baltic Fleet, bombed Königsberg and the bridgeheads of the Armeeabteilung 'Samland'.

Meanwhile Fort No. 8, which had been cut off from the rest of the defence, was nonetheless a significant pocket of resistance. After several unsuccessful attacks, several hundred Soviet soldiers, using both smoke screens to conceal their approach and flamethrowers to weaken the defences, managed to cross the moat and enter the fortress, where bitter close combat began. Once the outer defences had been weakened, a frontal assault succeeded in persuading the remainder of the garrison to surrender.

During this day, the 11^th Guards Army attempted to reach the Pregel river running east/west through the centre of the city, so eliminating all resistance in the southern half of the defence. But the Soviet advance was slowed in the central area of the city, where every building was, or could be, a defensive strongpoint which had to be destroyed. A particularly bitter skirmish took place in the main railway station and its platforms, where almost every item of rolling stock had been transformed into a firing point, and Soviet troops had to use armour and artillery support to advance, yet still took considerable losses. Only by dusk was the area completely cleared, allowing the attackers to approach the third and inner defence perimeter, protecting the entrance to the city centre itself.

In the north, Fort No. 5 proved to be a strong pocket of resistance. Soviet engineers finally managed to place explosives at the base of the walls, breaching them and allowing for a direct assault. As with the assault on Fort No. 8, there was bitter close combat in the fort, lasting all night and ceasing only in the morning when the few surviving Germans surrendered.

At the end of the day, seeing that continued resistance was pointless, General Otto Lasch, commanding the Festung 'Königsberg' and its three divisions, radioed Adolf Hitler’s headquarters to request but be peremptorily refused permission to surrender.

During the night the 11^th Guards Army crossed the Pregel and, despite German fire, established a bridgehead on the northern bank. Continuing its advance to the north, the 11^th Guards Army linked with the troops advancing from the north, completing the encirclement and isolating the city from the Armeeabteilung 'Samland'.

In the afternoon, Marshal Sovetskogo Soyuza Aleksandr M. Vasilevsky, co-ordinating the Soviet operations in East Prussia and the Baltic states, once again asked the defenders to surrender. This offer was refused and the German forces attempted to break out of the encirclement, attacking both from the city centre and the Samland bridgehead. The latter managed to advance a few miles before being brought to a standstill. Although another attack was prepared, the Germans' lack of air defences allowed Ilyushin Il-2 ground attack aircraft to destroy a large number of troops. During this campaign, Soviet aviation generally proved very effective.

By the end of the day it had become clear that any attempt by the Armeeabteilung 'Samland' to break out of the encirclement would be pointless. However, Soviet victory was not yet close, as almost 40,000 men were garrisoned in the city centre, which was regularly subjected to heavy shelling. During 9 April, the besieged German defenders were overwhelmed and the co-ordination of the defence disintegrated. Realising that continued resistance was futile, Lasch decided on his own initiative to send emissaries to negotiate the surrender. At 18.00, these emissaries reached the Soviet lines, and a delegation was sent to Lasch’s bunker. Shortly before 24.00, the surrender was acknowledged and 80,000 German soldiers were taken prisoner.

The battle had pitted 250,000 Soviet soldiers against 130,000 German troops, and among these the casualties were 60,000 Soviet and 50,000 German troops.

World War II resulted in the destruction of almost 80% of Königsberg, first by the RAF in August 1944 and then by Soviet bombing and shelling in April 1945. Almost all German residents who remained at the end of the war, an estimated 200,000 out of the city’s pre-war population of 316,000, were expelled from the city to make room for Soviet arrivals in what now became Kaliningrad.