The 'East Carpathian Strategic Offensive Operation' was a Soviet undertaking designed to aid the Slovak National Rising and allow the arrival of major Soviet forces into Transcarpathian Ukraine and Slovakia after taking the Dukla pass though the Carpathian mountains (8 September/28 October 1944).

On 29 August there began in Slovakia an uprising against the pro-Nazi government led by Stefan Tiso. However, the forces involved were wholly unequal, and the German forces quickly began to exert strong pressure on the much smaller and far less well-equipped Slovak nationalist forces, which on 31 August called on the Soviet government for support.

The nearest major Soviet formation was Marshal Sovetskogo Soyuza Ivan S. Konev’s 1^st Ukrainian Front, and its commander proposed to the Soviet supreme command that his front an operation to provide assistance to the nationalists. On 2 September the Stavka ordered an offensive on the junction of the 1^st Ukrainian Front and General Polkovnik (from 26 October General) Ivan Ye. Petrov’s 4^th Ukrainian Front with the object of advancing from the Krosno area of southern Poland to Dukla and thence to Presov in north-eastern Slovakia, where it would come into contact with the nationalist forces.

During its pursuit of the German forces after the end of the 'Lwów-Sandomierz Strategic Offensive Operation' at the end of August, the left wing of the 1^st Ukrainian Front (General Polkovnik Kirill S. Moskalenko’s 38^th Army, reinforced by General Major Fyedor G. Anikushkin’s XXV Tank Corps, General Leytenant Viktor K. Baranov’s I Guards Cavalry Corps and General Leytenant Ludvík Svoboda’s I Czechoslovak Corps), part of General Leytenant Stepan A. Krasovsky’s 2^nd Air Army) and Petrov’s 4^th Ukrainian Front (General Polkovnik Andrei A. Grechko’s 1^st Guards Army, General Leytenant Yevgeni P. Zhuravlev’s 18^th Army, XVII Guards Corps and General Leytenant Vasili N. Zhdanov’s 8^th Air Army) had reached the north-eastern foothills of the eastern part of the Carpathian mountains and established themselves on along a line from the area to the north-west of Kryno via Sanok and Skole to Krasnoilsk, and at this time these forces totalled 246,000 men, 322 tanks and self-propelled guns, 5,140 pieces of artillery and mortars, and 1,165 combat aircraft.

In the area into which the Soviet offensive was to debouch, the Germans forces were based on part of Generaloberst Josef Harpe’s Heeresgruppe 'Nordukraine', which on 23 September was redesignated as Heeresgruppe 'A': this part of the army group was Generaloberst Gotthard Heinrici’s Armeegruppe 'Heinrici', which controlled Heinrici’s own 1^st Panzerarmee and Vezérezredes Béla Miklós von Dalnoki’s [from 16 October Altábornagy László Dezsöo’s] Hungarian 1^st Army, and air support was provided by part of Generalleutnant Alexander Holle’s (from 27 September Generaloberst Otto Dessloch’s Luftflotte IV. Facing the latest Soviet onslaught were some 20 divisions for a total strength of up to 300,000 men with 100 tanks and assault guns, 3,250 pieces of artillery and mortars, and 450 aircraft.

The German-led forces occupied a powerful defensive system, which had a depth in the order of 37 miles (60 km) in the Carpathian mountains, and the Soviets, appreciating that creating a breakthrough would be difficult, undertook what was for them a comparatively lengthy preparation.

The concept of the 'East Carpathian Strategic Offensive Operation' was in effect the first stage of the Soviet plan to take the whole of Czechoslovakia by the 1^st Ukrainian Front, 2^nd Ukrainian Front and 4^th Ukrainian Front. With the success of the 2^nd Ukrainian Front’s 'Bucharest-Arad Offensive Operation' in reaching the rear of the German-led group of forces behind the Carpathian mountains, the Soviets could embark on the seizure of Slovakia, the eastern part of Czechoslovakia, without crossing the eastern part of the Carpathian mountains, by striking at the Germans and Hungarians from the east rather than the north-east. On 26 August, therefore, the Stavka ordered the 4^th Ukrainian Front to postpone its previously planned operation and go over to a tough defence, but then the situation changed dramatically when the leadership of the uprising in Slovakia asked the Soviet government to provide urgent military assistance.

On 2 September, Konev sent a written report to Iosif Stalin, the Soviet supreme commander-in-chief, about the flight of a group of Slovak aircraft to Soviet-held territory on 30 August. Konev informed Stalin that Plukovnik V. Talski, the deputy commander of the Slovak corps, said that in the event of a Soviet offensive to the west, the Slovak 1^st and 2^nd Divisions located on the Czechoslovak/Polish border could advance on Krosno to meet the Soviet advance.

The Soviets fully appreciated the fact that an advance over the Carpathian mountains from the east was, from the military point of view, an undertaking fraught with many difficulties. However, the political desirability of aiding the Czechoslovak people dictated the decision to strike in the Carpathian mountains despite the operational problems of doing so. Stalin therefore ordered the 1^st Ukrainian Front to prepare and implement an offensive from the area of Krosno and Sanok area in south-eastern Poland the general direction to Presov, reach the Slovak border and link with the Slovak forces. At the same time, Petrov’s 4^th Ukrainian Front was instructed to strike the German and Hungarian forces with its right wing from the Sanok area toward Comanca in order to reach the Slovak border and also link with the Slovak forces. In order to aid the 4^th Ukrainian Front in crossing the Carpathian mountains and taking the area of Uzhgorod, Chop an Mukachevo, the Stavka on 5 September instructed Marshal Rodion Ya. Malinovsky’s 2^nd Ukrainian Front to strike from the south through Brașov and Sibiu in the direction of Cluj.

The entire operation was planned as a five-day undertaking to advance between 55 and 60 miles (90 and 95 km).

For the main attack, the 1^st Ukrainian Front’s 38^th Army, reinforced with the XXV Tank Corps, I Guards Cavalry Corps and I Czechoslovak Corps, was to strike from the Krosno area to break through the German defences on a 5-mile (8-km) front. The 1^st Guards Army, reinforced with several tank and artillery formations and units, was to break through the German defences in the Sanok area, striking in the general direction of Comancha. The strategic grouping was created with parts of three combined-arms armies and two separate infantry corps, one tank corps, one cavalry corps and sizeable reserve and reinforcement elements. The ground forces were to be provided with air support by two air armies.

In overall terms, the defeat of the German and Hungarian forces was effected by the Soviet commitment of a number of small offensives to dislocated the German and Hungarian forces and drive them out of their prepared defences. The fighting took on a protracted nature, and was conducted at a relatively slow pace, and the struggle for the relevant mountain passes came to be of major importance.

In Soviet history, the 'East Carpathian Strategic Offensive Operation' was divided into two operational phases or sub-operations, namely the 'Carpathian-Dukla Offensive Operation' by the 1^st Ukrainian Front, and the 'Carpathian-Uzhgorod Offensive Operation' by the 4^th Ukrainian Front. The operation began in the 1^st Ukrainian Front’s sector on 8 September, and in the 4^th Ukrainian Front’s sector on 9 September. In both sectors, the German and Hungarian forces, which occupied advantageous defensive positions, offered a very stubborn resistance.

Determined to keep their hold on Slovakia and Transylvania, the Germans began to group substantial forces in the area where their defences had been broken in the Soviet forces' initial surge. This forced the Soviets to reinforce their advancing forces with two tank corps. The situation was such that the Soviet troops, at the request of the Czechoslovak government, had to carry out, as a matter of great urgency, an operation to assist the Slovak national uprising.

In the six days allotted for the operation’s preparation, the 4^th Ukrainian Front was reinforced by the III Mountain Corps, parts of which already had experience of mountain warfare as they had been committed in the Caucasian and Crimeans theatres and had special equipment, as well as four mountain-pack mortar regiments, two tank brigades, two self-propelled gun regiments and two mining engineer brigades.

On 8 September, the 38^th Army went over to the offensive, and on 9 September the right-wing formations of the Ist Guards Army followed. Attacking in the very difficult conditions of forested mountain terrain and in adverse weather conditions: the conditions made matters especially difficult for the provision of air support by the 2^nd Air Army and 8^th Air Army. By the middle of September the Soviet armies had advanced between 7.5 and 14.33 miles (12 and 23 km) and penetrated deeply into the German and Hungarian defences, but had yet to fulfil their assigned task of linking with the Slovak rebels and partisans. The German and Hungarians managed to create strengthened forces in the most threatened areas, transferring to them as many as five infantry divisions withdrawn from sectors that were not under attack by the 4^th Ukrainian Front’s 18^th Army and XVII Guards Corps.

In order to deprive the Germans and Hungarians of this opportunity to redeploy forces from unthreatened to threatened sectors, and thereby ease the situation faced by the shock group, on 18 September the 18^th Army and the XVII Guards Corps also went over to the offensive, widening the offensive’s front to some 250 miles (400 km). Employing the tactic of bypassing the German and Hungarian strongpoints and centres of resistance, the 18^th Army crossed the main sector of the Carpathian mountains on 18 September and began to develop its offensive toward Uzhgorod and Mukachevo. On 16 October, the XVII Guards Corps captured the western Ukrainian city of Rakhov, and the, in co-operation with the 2^nd Ukrainian Front’s 40^th Army, the city of Sighet in north-western Romania, and then with the main forces developed an offensive toward Chop. The 38^th Army’s and 1^st Guards Army’s operations were less successful.

By the end of September, Soviet and Czechoslovak soldiers forces had reached the main ridge of the Carpathian mountains. Having broken through the defences in the area of ​​the Łupków pass, on 20 September Soviet forces reached the Polish/Czechoslovak border. On the following day, Soviet troops took their first Czechoslovak village, namely Kalinov.

On 6 October, the I Czechoslovak Corps, after taking the Dukla pass together with the Soviet troops of the 38^th Army’s LXVII Corps and XXXI Tank Corps, entered its men’s native land, freeing the village of Vysný Komárnik. Repeated attempts to effect a complete breakthrough of the German and Hungarian resistance were unsuccessful, however. The 1^st Guards Army continued to fight in certain areas using small reconnaissance and probing groups. The 38^th Army fought stubborn battles to the south-west of the Dukla pass to obtain control of the exit to the Ondava river valley. The 18^th Army and the XVII Guards Corps, drawing on the success of the 2^nd Ukrainian Front, continued to develop the offensive in Transcarpathian Ukraine, liberating the cities of Mukachevo and Uzhgorod on 26 and 27 October respectively. The 4^th Ukrainian Front continued the offensive together with the 1^st and 2^nd Ukrainian Fronts: on 28 October the 38^th Army and the 1^st Guards Army fought for the passes of the main part of the Carpathian mountains, and the 18^th Army and the XVII Guards Corps reached the line between Stakchin and the Tisza river via Sobrantse, Pavlovce and Chop, where their advance was delayed by counterattacks delivered by fresh German forces.

Right to the end of October, Soviet and Czechoslovak troops fought heavy, bloody battles against German forces stubbornly defending in the mountains. The Soviet and Czechoslovak forces achieved considerable success, but could not break through to the Slovak rebels before the 'East Carpathian Strategic Offensive Operation' came to an end on 28 October, when both of the fronts and the I Czechoslovak Corps went over to the defensive.

With the failure of the Soviet forces to break through to its forces, the Slovak National Rising was suppressed on 28 October, although partisans continued to fight until the final Soviet seizure of Czechoslovakia.

Thus Germany had gained a limited strategic victory as the object of the Soviet operation was not achieved, and the Germans had managed to halt the Soviet offensive and suppress the Slovak National Rising. Nonetheless, the Soviet had achieved a operational victory inasmuch as they had completed the liberation of Ukraine and shifted the war forward into Czechoslovakia.