The 'Debrecen Offensive Operation' was the Soviet undertaking to advance from western Romania into eastern Hungary (6/28 October 1944).

The undertaking was the responsibility of Marshal Sovetskogo Soyuza Rodion Ya. Malinovsky’s 2^nd Ukrainian Front against the defences of General Maximilian Fretter-Pico’s German 6^th Army of Generaloberst Johannes Friessner’s Heeresgruppe 'Süd', together with the formations of Vezérõrnagy Géza Vörös’s (from 17 October Altábornagy János Markóczy’s) Hungarian VII Corps. In the course of this Soviet offensive, the Axis forces retreated about 100 miles (160 km) and lost the city of Debrecen, which was the Soviet strategic objective.

In the middle of August 1944 Heeresgruppe 'Südukraine', which became Heeresgruppe 'Süd' on 23 September, was on the verge of collapse. To the north, 'Bagration' was currently completing the destruction of Generaloberst Georg-Hans Reinhardt’s Heeresgruppe 'Mitte'. On 25 August Germany’s ally Romania had switched sides and declared war on Germany and Hungary, and the continued drive of General Fedor I. Tolbukhin’s 3^rd Ukrainian Front into Romania then destroyed any semblance of an organised defensive line in that country. On 8 September Bulgaria, another German ally, also switched sides and declared war on Germany. By this time the 3^rd Ukrainian Front, aided on its left by Malinovsky’s 2^nd Ukrainian Front, had destroyed 13 Axis divisions, in the process taking more than 100,000 prisoners, and for their successes Malinovsky and Tolbukhin were promoted to the rank of Marshal Sovetskogo Soyuza on 10 and 12 September respectively.

The defections of Bulgaria and Romania had opened a 400-mile (650-km) gap in the front held by Heeresgruppe 'Südukraine', and as Friessner tried desperately to create a new defensive line, intelligence information reaching the German high command indicated that the Hungarian leader, Vezérfökapitány Miklós Horthy, was preparing to sign a separate peace with the USSR. Should this happen, the whole of Germany’s south-eastern front would collapse.

Fretter-Pico’s 6^th Army was the core of Heeresgruppe 'Süd' and, appreciating that the Hungarians were suffering from low morale, Friessner attached Altábornagy Lajos Veres von Dalnoki’s (from 16 October Altábornagy Jenö Major’s) Hungarian 2^nd Army to Fretter-Pico’s 6^th Army to create the so-called Armeegruppe 'Fretter-Pico'.

As Tolbukhin’s 3^rd Ukrainian Front cleared the remaining resistance in Romania, Malinovsky’s 2^nd Ukrainian Front started to advance toward Hungary, but slowed as its advance continued. The delay in the arrival of the 2^nd Ukrainian Front offered Friessner time just sufficient for the establishment of a weak defensive line based on the Mureş river. Early in September 1944, Malinovsky received orders from the Stavka to advance from Cluj in the direction of Miskolc, Debrecen and the Tisza river, and thence onto the flat expanses of the Hungarian plain. Once his forces had reached this steppe area, Malinovsky could exploit his overwhelming advantage in armour to destroy Heeresgruppe 'Süd', break through to Budapest, and advance still farther into Slovakia.

However, Malinovsky’s plan did not take into account the presence of Panzer reserves that had been ordered into the area by Adolf Hitler. Furthermore, the Soviet forces had been worn down by the Jassy-Chisinau and Belgrade operations, and also had to contend with logistical difficulties resulting from the different railway gauge used in Romania.

Fearing an envelopment of his forces by Malinovsky’s 2^nd Ukrainian Front and General Ivan Ye. Petrov’s 4^th Ukrainian Front from the south and north respectively, Friessner flew to Hitler’s headquarters and asked for authorisation to withdraw his forces to defensive positions along the Tisza river. Friessner argued that this withdrawal would provide his formations with some freedom of movement to counter the continuing Soviet attacks. Almost inevitably, Hitler refused to allow any such move, instead promising reinforcements for Heeresgruppe 'Süd', and even demanded that Friessner start a new offensive from Cluj with the aim of destroying two of Malinovsky’s armies, namely General Polkovnik Sergei G. Trofimenko’s 27^th Army and General Polkovnik Andrei G. Kravchenko’s 6^th Guards Tank Army. In addition, he was ordered retake two vital passes in the southern part of the Carpathian mountains in order to sever Malinovsky’s lines of communication.

On 14 September Malinovsky’s 2^nd Ukrainian Front, in conjunction with Tolbukhin’s 3^rd Ukrainian Front, launched its own 'Belgrade Strategic Offensive Operation'. Friessner had been concentrating troops for the offensive he had been ordered to make, and the 2^nd Ukrainian Front encountered heavy resistance right from the start. After a week of fruitless attacks, Malinovsky called off his offensive and ordered Kravchenko’s exhausted 6^th Guards Tank Army, along with General Issa A. Pliyev’s Cavalry Mechanised Group 'Pliyev' (VII Mechanised, IV Guards Cavalry and VI Guards Cavalry Corps, with 389 tanks and assault guns) and General Leytenant Sergei I. Gorshkov’s Cavalry Tank Group 'Gorshkov' (V Guards Cavalry Corps and XXIII Tank Corps, with 146 tanks and assault guns), to the area near Oradea. Malinovsky planned to use this mobile armoured force as an operational exploitation force in future operations.

On 20 September Romanian troops captured the Romanian border town of Arad. Panicked by the arrival of the war on its own border, the Hungarian general staff activated Altábornagy József Heszlényi’s Hungarian 3^rd Army, a formation comprising new recruits and reservists, and thus of only the most limited military value. At the same time both pro-German and pro-Allied factions in the Hungarian government began taking measures to seize control of the country, and Horthy now pressed negotiations for an armistice with the Soviets.

Friessner was compelled to send several of his desperately needed reinforcement units to Budapest, to keep a careful eye on the situation, under the pretext of providing the units with a period of rest and refit.

By the end of September both Malinovsky and Friessner had received new orders. Malinovsky was now ordered to attack toward Budapest from the salient in the south around Arad. He was to use General Leytenant Ivan T. Shlemin’s 46^th Army and General Leytenant Vasile Atanasiu’s Romanian 1^st Army with the Cavalry Mechanised Group 'Pliyev' as the exploitation force in case of a successful breakthrough. The remainder of Malinovsky’s forces, including Kravchenko’s 6^th Guards Tank Army, General Leytenant Ivan M. Managarov’s 53^rd Army and Gorshkov’s Cavalry Tank Group 'Gorshkov', were to attack from the north, near Oradea, in the direction of Debrecen. The plan was for the two spearheads to link, so encircling the German forces, and then annihilate them.

Friessner’s new instructions included an attack from Oradea with the Armeegruppe 'Fretter-Pico' with the object of cutting through the Soviet line and capturing the passes across the Carpathian mountains, which his forces were to hold until the following spring.

This meant that both sides were attacking at the same time and in about the same place, and each side underestimated the forces opposing it 1 2. The Axis forces had some 80,000 men, and the Soviet forces about 260,000 men.

The 2^nd Ukrainian Front’s offensive began on 6 October as Malinovsky’s southern pincer attacked near Arad, and slicing through the Hungarian 3^rd Army, whose men soon abandoned their positions, and many divisions simply disappeared in the assault. The spearhead of the 2^nd Ukrainian Front’s southern pincer, followed by the Cavalry Mechanised Group 'Pliyev', advanced almost 37 miles (60 km) in the first day of the offensive. Getting under way on the same day, the attack by the 2^nd Ukrainian Front’s northern pincer had a considerably harder time of it after colliding with Thunert’s 1^st Panzerdivision and Radowitz’s 23^rd Panzerdivision of Breith’s III Panzerkorps, so by the end of the day the northern pincer had advanced just 6 miles (10 km).

Reacting quickly, Fretter-Pico ordered Abraham’s 76^th Division into the line near Oradea. This freed the 23^rd Panzerdivision to move to the south in an effort to counter the breakthrough near Arad. Pape’s Panzergrenadierdivision 'Feldherrnhalle', which was refitting at Mezokövesd, was moved into action to guard potential crossing points on the Tisza river.

By the evening of 7 October the 2^nd Ukrainian Front’s southern pincer had advanced farther toward the Tisza river, but the northern pincer was still stalled near Oradea, where the German and Hungarian forces had managed to halt several flanking attempts by the 6^th Guards Tank Army. Realising how firmly his northern pincer had been halted, Malinovsky decided to turn his southern pincer to the north in the direction of Debrecen in an attempt to draw Axis forces away from Oradea and so allow his northern pincer to break through and crush the German forces between the Cavalry Mechanised Group 'Pliyev' and the 6^th Guards Tank Army.

By 10 October the 2^nd Ukrainian Front had seized several bridgeheads on the western bank of the Tisza river, and elements of the 46^th Army and the XVIII Tank Corps were driving on Kecskemet, only 45 miles (70 km) distant from Budapest. Malinovsky now had to redistribute some of these forces to support the advance of the Cavalry Mechanised Group 'Pliyev' on the other side of the Tisza river, however, and after coming under attack by the Hungarian cavalry and German anti-aircraft troops, the remaining formations of the 2^nd Ukrainian Front’s spearhead were forced to pull back to the Tisza river on 11 October. On the same day, counterattacks in the Mindszent bridgehead by Ezredes Béla Tiszay’s (from 21 October Ezredes Zoltán Schell’s) Hungarian 1^st Armoured Division and Vezérõrnagy Ferenc Osztovics’s 23^rd Reserve-Division against the 2^nd Ukrainian Front’s 243^rd Division became so threatening that the Romanian VII Corps was pushed forward as reinforcement it. The Romanian 2^nd and 4^th Divisions then took over the bridgeheads of the 2^nd Ukrainian Front on the Tisza river below Szolnok.

On 19 October Vezérõrnagy Mihály Ibrányi’s Hungarian 1^st Cavalry Division and the 1^st Division attacked the bridgehead of the 4^th Division, which held until taken on its right flank by von Nostitz-Wallwitz’s 24^th Panzerdivision, SS-Brigadeführer und Generalmajor der Waffen-SS Fritz Schmedes’s 4^th SS Polizei Panzergrenadierdivision, and the 503^rd schwere Panzerabteilung. The Romanian division’s right flank collapsed and the German armour punched through behind the division, cutting it off from the Tisza river and forcing the division to surrender by 20 October.

On 25 October, the Hungarian 1^st Cavalry Division, 1^st Division and 20^th Division attacked the Romanian 2^nd Division in its bridgehead, causing the Romanians to panic and pull back across the Tisza river. This Hungarian success was not repeated when a third assault was made during 26/29 October against the Romanian 19^th Division’s bridgehead at Alpar.

Meanwhile, on 8 October the Cavalry Mechanised Group 'Pliyev' had moved its attack to the north-east and advanced quickly along the major road linking Szolnok and Debrecen. At Hajdúszoboszló, the group’s leading formations, the IX Guards Mechanised Corps and VI Guards Cavalry Corps, ran into elements of 23^rd Panzerdivision moving to the south in order to halt the Soviet southern pincer. With powerful air support by General Polkovnik Sergei K. Goryunov’s 5^th Air Army, on 9 October Pliyev’s group took the town and the Germans fell back to Debrecen, where they started to prepare defences in the area to the town’s south-east, and then drove back several heavy Soviet attacks.

The Cavalry Mechanised Group 'Pliyev' now redirected its attack once again. Now moving back toward Oradea, its advance was slowed by determined German and Hungarian defence. Even so, it was clear that Pliyev would be able to link with the 6^th Guards Tanks Army, completing the encirclement and thus shattering Fretter-Pico’s line.

On 10 October Fretter-Pico ordered Thunert’s 1^st Panzerdivision and Schmidhuber’s 13^th Panzerdivision to attack to the west and to the east respectively. This cut off the three corps of the Cavalry Mechanised Group 'Pliyev', whose commander had left his flanks relatively lightly defended. The two experienced Panzer formations soon met near the town of Püspökladány.

What at first looked like a crisis point for the Germans under Fretter-Pico had now been turned into a possible disaster for the Soviets under Malinovsky. The latter, realising the danger to Pliyev’s group, halted his attack in the south and focused all his forces on reaching the trapped mobile group. Fretter-Pico ordered the Panzergrenadierdivision 'Feldherrnhalle' to Debrecen. The situation on the ground was greatly confused, with neither the Soviets nor the Germans knowing who was surrounding whom.

On 11 October elements of Pliyev’s IV Guards Cavalry Corps reached the outskirts of Debrecen. Although this corps was cut off from the main Soviet force, Pliyev had managed to avoid encirclement. Under the 6^th Guards Tank Army’s strongly delivered attacks, the front line near Oradea was steadily pushed back. By 12 October Pliyev’s group had already lost some 200 armoured fighting vehicles.

By 14 October the German and Hungarian line had fallen back 8.75 miles (14 km), and Oradea was finally occupied by Malinovsky’s forces.

Farther to the north, a new crisis threatened Fretter-Pico. In this sector Petrov’s 4^th Ukrainian Front had finally attacked, falling on General Otto Wöhler’s 8^th Army, which was in danger of collapsing under the weight of the Soviet attack.

On 15 October Horthy announced that Hungary had accepted an armistice with the USSR. Reacting quickly, Hitler ordered SS-Obersturmbannführer Otto Skorzeny to launch 'Panzerfaust', and by 16 October Skorzeny and his SS paratroopers had averted disaster by blackmailing Horthy into resigning and giving control of the government to Ferenc Szálasi, a pro-German leader.

Malinovsky now linked with the Cavalry Mechanised Group 'Pliyev', and ordered the continued advance of the Soviet forces with the aim of taking Debrecen and then swinging to the north in the direction of Nyíregyháza. If he could take this, Malinovsky would sever the 8^th Army's line of communications.

In response to the Soviet attacks, the German and Hungarian forces of the Armeegruppe 'Fretter-Pico' fought tenaciously, and turned each village and crossroads into a defensive position.

Forcing their way through the Axis resistance, on 19/20 October three Romanian divisions (General de brigadâ Constantin Iordachescu’s 2^nd Mountain Division, General de brigadâ Leonard Mociulschi’s 3^rd Mountain Division and 1^st 'Tudor Vladimirescu' Division, the last recruited by the USSR from Romanian prisoners of war during 1943) assaulted and seized Debrecen as part of 27^th Army’s assault on the right flank of the 6^th Guards Tank Army.

On 22 October, Pliyev’s group captured Nyíregyháza, so severing the 8^th Army's lines of communication. Friessner had ordered Wöhler to disengage and fall back to the north-west of Nyíregyháza and attempt to form a defensive line, and this move was already in progress when the Cavalry Mechanised Group 'Pliyev' cut the army’s lines of communication. Friessner’s chief-of-staff, Generalmajor Helmuth von Grolman, now proposed a plan pregnant with risk: believing that the first encirclement of Pliyev’s group had failed because of the confusion of the German and Hungarian forces and the lack of large enough forces to effect the encirclement, von Grolman now argued that the situation had changed and that an encirclement was feasible. Friessner approved the plan.

The 1^st Panzerdivision and 23^rd Panzerdivision, spearheaded by the Tiger II heavy tanks of the 503^rd schwere Panzerabteilung, would attack to the east. Generalleutnant Paul Klatt’s 3^rd Gebirgsdivision, Generalmajor Hans Längenfelder’s 15^th Division, and SS-Brigadeführer und Generalmajor der Waffen-SS Joachim Rumohr’s 8^th SS Kavalleriedivision 'Florian Geyer' were the formations attacking to the west. The 13^th Panzerdivision, Panzergrenadierdivision 'Feldherrnhalle' and 46^th Division would be held back to counter any Soviet break-out attempt.

The German attack started on 23 October, and quickly broke through the infantry corps defending the lines of communication of the Cavalry Mechanised Group 'Pliyev'. At 02.00 on 24 October the 23^rd Panzerdivision reached Nagykálló, which had already been occupied by the 3^rd Gebirgsdivision, and this completed the encirclement of Pliyev’s group. As the corps of the Cavalry Mechanised Group 'Pliyev' launched probing attacks in an effort to find an escape route, they quickly discovered that there was no way out.

The German and Hungarian forces now started to close in on the trapped Soviet formation. Malinovsky sent Soviet forces to the north in an effort to break through to the Pliyev’s group, but these were met by a determined Axis resistance and their advance was soon bought to a halt. Realising that his formation’s plight was great, Pliyev ordered attacks to break the encirclement. The German and Hungarian lines held, however, and by the evening of 24 October Pliyev realised that his formation’s only hope of escape was a breakthrough by other Soviet forces.

Malinovsky launched a major assault on 25 October, only to be halted by the counterattack of the 1^st Panzerdivision and the 128^th Panzergrenadierregiment of the 23^rd Panzerdivision. On the same day the Cavalry Mechanised Group 'Pliyev' attempted to break out through the positions of the 3^rd Gebirgsdivision, but this latter held its ground against the Soviet armour, inflicting many casualties. On 26 October the 23^rd Panzerdivision recaptured Nyíregyháza.

The Soviet forces had carried out widespread atrocities during their occupation, including looting, mass rapes and the murder of civilians. This steeled the resolve of the German and, more especially, the Hungarian troops. When Malinovsky launched his next assault, he was met by the most ferocious defence yet encountered.

Meanwhile, Wöhler began moving his 8^th Army out through the escape route created through Nyíregyháza. By 28 October the 8^th Army had escaped from the encirclement, and the circle around Pliyev’s group would not be broken. On 29 October the survivors of Pliyev’s shattered forces destroyed their vehicles and heavy weapons and marched to the south in an effort to regain the Soviet lines on foot.

The Axis losses in the 'Debrecen Offensive Operation' had been 11,900 men killed and 6,660 missing, 358 armoured fighting vehicles, 310 pieces of artillery, 610 anti-tank guns and 247 mortars; those of the Soviet and allied forces had been 19,715 men killed or missing, 500 armoured fighting vehicles, and 1,656 guns and mortars. Three corps of the 2^nd Ukrainian Front had sustained significant losses in the fighting.

The intended swift assault on Budapest by the 2^nd Ukrainian Front had been delayed, and Hungarian troops remained in the war as German allies until the end of the war in Europe. The Nyíregyháza counterattack was the last time that German forces met and defeated a full-strength major Soviet formation on even terms. By pinching off the breakthrough exploitation group of the 2^nd Ukrainian Front offensive, the Germans were able to re-establish a stable position, and prevent the 2^nd Ukrainian Front advance from becoming a catastrophe for the 8^th Army. The German success was short-lived, however, for Nyíregyháza was recaptured by Soviet troops on 30 October, and another powerful Soviet offensive opened to the south, with Budapest again the objective, reaching the area of the Hungarian capital on 4 November.

While the 2^nd Ukrainian Front was denied the swift seizure of the Hungarian capital, the 'Debrecen Offensive Operation' saw its forces advance anywhere from 60 to 120 miles (100 to 195 km) farther to the west into Hungary, positioning the 2^nd and 3^rd Ukrainian Fronts nicely for a renewed offensive toward Budapest, a task made easier by the fact that the tank battle at Debrecen had drawn the Panzer units away from the defences of the approaches to the Hungarian capital.

Finally, the Soviet thrust occupied the eastern third of Hungary, clearing the obstacle of the Transylvanian Alps and denying the Axis forces their use as a winter defence position.