The 'Kiev Defensive Operation' was the Soviet defence of Kiev and northern Ukraine against the advance of the German and allied forces of Generalfeldmarschall Gerd von Rundstedt’s Heeresgruppe 'Süd' in the later stages of 'Barbarossa' (23 August/26 September 1941).

Known to the Germans as the 1^st Battle of Kiev, the 'Kiev Strategic Defensive Operation' was a defeat of unprecedentedly huge size after very substantial Soviet forces had been trapped in a very large encirclement in the vicinity of Kiev: the episode is generally considered to have been the largest encirclement of troops in history. So far as the Germans were concerned, this stage of the campaign lasted from 7 August to 26 September as their forces surged to the east in the middle stage of 'Barbarossa', but in Soviet military history this period became known as the 'Kiev Strategic Defensive Operation' with a start date of 7 July.

In Soviet terminology, the components of the 'Kiev Strategic Defensive Operation' were the 'Korosten Defensive Operation' (11 July/20 August), the 'Novohrad-Volynskyi Defensive Operation' (10 July/20 August), the 'Uman Defensive Operation' (15 July/4 August), the 'Tiraspol-Melitopol Defensive Operation' (27 July/28 September), the 'Kiev-Priluki Defensive Operation' (20 August/26 September) and the 'Malyn Offensive Operation' (5/8 August).

Almost the whole of the Soviets' South-West Direction was encircled and trapped, and the Germans claimed eventually to have taken 665,000 Soviet prisoners. The Kiev encirclement was never fully completed, however, and small groups of Soviet troops managed to escape the encirclement (known to the Germans as a cauldron) in the days after the German pincers met to the east of the city. Elements which managed to escape included the headquarters of Marshal Sovetskogo Soyuza Semyon M. Budyonny and Marshal Sovetskogo Soyuza Semyon K. Timoshenko, but the commander of the South-West Front, General Polkovnik Mikhail P. Kirponos, was trapped in the cauldron and killed while trying to break out.

The Kiev disaster was of huge proportions for the Soviets, and even exceeded the disaster of the Minsk pocket of June and July 1941. On 1 September, the South-Western Direction totalled between 752,000 and 760,000 first-lines troops within a figure of 850,000 men including reserves and rear-area elements, 3,923 pieces of artillery and mortars, 114 tanks and 167 warplanes. Of these, 452,700 men, 2,642 pieces of artillery and mortars, and 64 tanks were trapped in the encirclement, of which as few as 15,000 men managed to escape from the encirclement by 2 October. In overall terms, the South-Western Direction suffered 700,544 casualties, including 616,304 men killed, missing or taken prisoner in the month-long 1^st Battle of Kiev: General Major Mikhail I. Potapov’s 5^th Army, General Major Anton I. Lopatin’s 37^th Army, General Leytenant Fyedor Ya. Kostenko’s 26^th Army and General Major Fyedor I. Kuznetsov’s 21^st Army, totalling 43 divisions, effectively ceased to exist, and General Major Nikolai V. Feklenko’s 38^th Army and General Major Kuzma P. Podlas’s 40^th Army were also very hard hit but managed to survive. Like the Western Direction before it, the South-Western Direction had then to be re-created almost from the ground up.

The rapid eastward advance of Generalfeldmarschall Fedor von Bock’s Heeresgruppe 'Mitte' through the central sector of the Eastern Front had created a huge salient around its junction with von Rundstedt’s Heeresgruppe 'Süd' by a time late in July 1941, and in this salient was located a substantial proportion of the Soviet army on the Eastern Front, in the form of almost all of the South-Western Direction, positioned in and around Kiev. While lacking mobility and armour as a result of its major losses of tanks in the Battle of Uman (15 July/8 August), the South-Western Direction was nonetheless a major threat to the continued German advance and was, in fact, the largest single concentration of Soviet troops on the Eastern Front at that time.

On 3 August Adolf Hitler temporarily delayed the drive straight to Moscow in favour of the advance farther to the south and the seizure of Kiev, the largest city in Ukraine. On 12 August, however, a the issue of a supplement to the Führerweisung Nr 34 represented a compromise between Hitler, who was convinced the correct strategy was to clear the salient occupied by Soviet forces on the right flank of Heeresgruppe 'Mitte' in the Kiev area before any resumption of the drive on Moscow, and a trio of his senior commanders. These were Generaloberst Franz Halder, chief of the Oberkommando des Heeres’s general staff, von Bock and Generaloberst Heinz Guderian, commander of the 2^nd Panzergruppe, all of whom advocated the continued advance on Moscow as soon and as rapidly as possible. The compromise required Guderian’s 2^nd Panzergruppe and Generaloberst Hermann Hoth’s 3^rd Panzergruppe of Heeresgruppe 'Mitte', which were in the process of redeployment to support Generalfeldmarschall Wilhelm Ritter von Leeb’s Heeresgruppe 'Nord' and von Rundstedt’s Heeresgruppe 'Süd' respectively, be returned to von Bock’s Heeresgruppe 'Mitte', together with Generaloberst Erich Hoepner’s 4^th Panzergruppe of Heeresgruppe 'Nord', once their objectives had been achieved. Under the control of Heeresgruppe 'Mitte', the three Panzergruppen were then to spearhead the advance on Moscow. Halder and von Bock were initially satisfied by the compromise, but their optimism rapidly disappeared as the operational realities of the plan began to emerge as being too challenging.

On 18 August the Oberkommando des Heeres submitted to Hitler a strategic survey about the continuation of operations on the Eastern Front. The survey made the case for the drive to Moscow, arguing once more than Heeresgruppe 'Nord' and Heeresgruppe 'Süd' already possessed sufficient strength to accomplish the objectives assigned to them without assistance from Heeresgruppe 'Mitte', and emphasising that there was left enough time before the onset of winter for only one decisive operation against Moscow.

Hitler rejected the survey’s proposals on 20 August, citing his belief that the most important objective for the German forces was to deprive the Soviets of their industrial areas. On 21 August General Alfred Jodl, the chief of the operations staff of the Oberkommando der Wehrmacht, issued to Generalfeldmarschall Walther von Brauchitsch, the commander-in-chief of the army, a directive summarising Hitler’s instructions. The directive re-emphasised that the capture of Moscow before the onset of winter was an objective secondary to a series of primary objectives including the seizure of Crimea and the industrial and coal region of the Don river basin, the isolation of the oil-producing regions of the Caucasus from the rest of the USSR, and in the north the encirclement of Leningrad and the establishment of a land connection with the Finnish army. Among other instructions, it also laid it down that Heeresgruppe 'Mitte' was to allocate sufficient forces to ensure the destruction of the 'Russian 5^th Army' (i.e. the Soviet forces in the salient centred on Kiev) and simultaneously to prepare to defeat any Soviet counter-offensives in the central sector of its front. Halder was dismayed, later describing Hitler’s plan as an unacceptable expression of wishful thinking, and concluded that the orders were contradictory, that it was Hitler alone who must bear the responsibility for the inconsistency of his orders, and that the Oberkommando des Heeres could no longer assume responsibility for what was occurring. However, Hitler’s instructions still accurately reflected the original intent of the 'Barbarossa' directive, of which the Oberkommando des Heeres had for a long time been aware. Halder offered his resignation and advised von Brauchitsch to do the same. However, von Brauchitsch declined, stating Hitler would not accept the gesture, and that in any case nothing would be changed. Halder then withdrew his offer of resignation.

On 23 August, Halder met von Bock and Guderian in the Belorussian city of Borisov, and then travelled by air with Guderian to Hitler’s headquarters in East Prussia. During a meeting between Guderian and Hitler, with neither Halder nor von Brauchitsch present, Hitler allowed Guderian to make the case for driving on to Moscow, but then rejected his argument and said that his decision to secure the northern and southern sectors of the USSR’s western regions were 'tasks which stripped the Moscow problem of much of its significance' and was 'not a new proposition, but a fact I have clearly and unequivocally stated since the beginning of the operation'. Hitler also argued that the situation was yet more critical as the opportunity to encircle the Soviet forces in the salient was 'an unexpected opportunity, and a reprieve from past failures to trap the Soviet armies in the south'. Hitler also added that 'the objections that time will be lost and the offensive on Moscow might be undertaken too late, or that the armoured units might no longer have the technical capability to fulfil their mission, are not valid'. Hitler reiterated that once the flanks of Heeresgruppe 'Mitte' had been cleared, and especially the salient in the south, then he would permit the army to resume its drive on Moscow, which was an offensive which must not fail. In point of fact Hitler had already issued the orders for the shift of Guderian’s 2^nd Panzergruppe to the south. Guderian thereupon returned to his command and began the southern thrust in an effort to encircle the Soviet forces in the salient.

Most of the 2^nd Panzergruppe and Generaloberst Maximilian Reichsfreiherr von Weichs’s 2^nd Army were detached from Heeresgruppe 'Mitte' and despatched to the south with the task of encircling Budyonny’s South-Western Direction in conjunction with Generaloberst Ewald von Kleist’s 1^st Panzergruppe of Heeresgruppe 'Süd', which was driving to meet them from the south-east.

The Panzergruppen made rapid progress. On 12 September von Kleist’s 1^st Panzergruppe, which had by now turned to the north and crossed the Dniepr river, burst from its bridgeheads at Cherkassy and Kremenchug, continued to the north and cut across the rear of Budyonny’s South-Western Direction. On 16 September it made contact with Guderian’s 2^nd Panzergruppe, which was advancing to the south, at the town of Lokhvitsa, some 120 miles (195 km) to the east of Kiev. Budyonny’s forces were now trapped, and Premier Iosif Stalin removed Budyonny from command on 13 September, but named no successor and thus left the encircled troops to their individual army, corps and divisional commanders.

At this point the fate of the encircled Russian formations was sealed. With no mobile forces and no overall commander, the Soviet formations faced the impossibility of planning and attempting any beak-out. The infantry of General Carl-Heinrich von Stülpnagel’s 17^th Army and Generalfeldmarschall Walther von Reichenau’s 6^th Army of Heeresgruppe 'Süd' soon arrived, along with von Weichs’s 2^nd Army also on loan from Heeresgruppe 'Mitte' and advancing behind Guderian’s armoured forces. These infantry formations began the systematic process of reducing the pocket with the aid of the two Panzergruppen. The Soviet armies encircled in the Kiev area did not yield easily, and a savage battle, in which the Soviets were bombarded by artillery, tanks and warplanes, had therefore to be fought before the pocket was destroyed. By 19 September Kiev had fallen, but the encirclement battle continued. After 10 days of heavy fighting, the last remnants of troops to the east of Kiev surrendered on 26 September.

The Germans claimed to have captured 665,000 Soviet soldiers, but this total included a large number of civilians. The number of troops captured was probably in the order of 452,700 men, and in addition the Soviets had lost another 163, 600 men killed or wounded. The Germans had lost about 150,000 men dead or wounded from their starting total of 500,000 men.

After its defeat at Kiev, the Soviet army had no further reserves in the western USSR. To defend Moscow, now restored as the primary German objective, the Soviets could field 800,000 men in 83 divisions, but no more than 25 of these formations were fully equipped and staffed, and there was a huge shortage of tanks, motor vehicles and aircraft. On the German side, the losses sustained in the fighting for and round Kiev had exhausted the troops and worn out much of the equipment. Although the German could still field some 2 million men in 70 divisions, only 15% of these formations were motorised, and most of them had been depleted by operations to date despite the fact that their total characterised the highest proportion of motorised to infantry ratio in any German operation in the war to date.

Largely as a result of the southward wheel of Guderian’s 2^nd Panzergruppe to meet the northward thrust of von Kleist’s 1^st Panzergruppe, the Germans destroyed the entire South-Western Direction to the east of Kiev during September, inflicting huge losses on the Soviet army, while the Soviet forces to the west of Moscow conducted a series of futile and costly offensive operations against Heeresgruppe 'Mitte' near Smolensk. These operations, which included the 'Smolensk Offensive Operation' (21 July/7 August) and the 'Yelnya Offensive Operation' (30 August/8 September), were conducted over very bad terrain against defenders in fortified strongpoints, and nearly all of them ended in further disaster for the Soviet army. As a result of these failed offensives, the Soviet formations defending Moscow were seriously weakened. With its southern flank secured, Heeresgruppe 'Mitte' launched its 'Taifun' (i) offensive in the direction of Vyaz’ma during October.

Despite the objections of von Rundstedt, Heeresgruppe 'Süd' was ordered to resume the offensive and overran nearly all of Crimea and Ukraine before reaching the edges of the Donbass industrial region. However after four months of continuous operations von Rundstedt’s formations were on the very brink of total exhaustion, and suffered a major defeat in the Battle of Rostov (21/27 November). Heeresgruppe 'Süd''s infantry formations fared little better and failed to capture the vital city of Kharkov in the 1^st Battle of Kharkov (20/24 October) before nearly all of its factories, equipment and skilled work force had been evacuated to be replanted in the area to the east of the Ural mountains.

However, the need to complete the Kiev operation had delayed the German advance on Moscow for four weeks, a factor which can be argued as a decisive blow to the German ambitions of taking the Soviet capital as the delay allowed the advent of deep winter weather to intervene in favour of the Soviets. Moreover, while the German success in the Battle of Kiev was operationally very successful, it played no significant part in enhancing the German strategic position, because their primary objective, namely a decisive victory that would conclude the war, was not achieved.

Immediately after the end of World War II, prominent German commanders argued that had operations at Kiev been delayed and 'Taifun' (i) been launched in September rather than October, the Germans forces would have reached and captured Moscow before the onset of winter. Guderian and von Bock in particular fiercely argued that the sideshow to Kiev would have dire consequences if the operation dragged on for too long. Winter was imminent, and if Moscow had not been taken before the arrival of the first snow, the entire operation would have ground to a halt. Historians, on the other hand, have plausibly argued that had 'Taifun' (i) been launched in September, it would have met greater resistance as the Soviet forces would not have been weakened by their offensives to the east of Smolensk, and that the German offensive would also have been launched with an extended right flank.