[5][6] The Eastern Front was decisive in determining the outcome in the European theatre of operations in World War II, eventually serving as the main reason for the defeat of Nazi Germany and the Axis nations.

[35] The German Anschluss of Austria in 1938 and the dismemberment of Czechoslovakia (1938–1939) demonstrated the impossibility of establishing a collective security system in Europe,[36] a policy advocated by the Soviet ministry of foreign affairs under Maxim Litvinov.

[47] By the time of the invasion of the Soviet Union, the Wehrmacht consisted of c. 3,800,000 men of the Heer, 1,680,000 of the Luftwaffe, 404,000 of the Kriegsmarine, 150,000 of the Waffen-SS, and 1,200,000 of the Replacement Army (contained 450,400 active reservists, 550,000 new recruits and 204,000 in administrative services, vigiles and or in convalescence).

As in the Sino-Soviet conflict on the Chinese Eastern Railway or Soviet–Japanese border conflicts, Soviet troops on the western border received a directive, signed by Marshal Semyon Timoshenko and General of the Army Georgy Zhukov, that ordered (as demanded by Stalin): "do not answer to any provocations" and "do not undertake any (offensive) actions without specific orders"[citation needed] – which meant that Soviet troops could open fire only on their soil and forbade counter-attack on German soil.

[59]: 122  The rest were foodstuff, nonferrous metals (e.g., copper, magnesium, nickel, zinc, lead, tin, aluminium), chemical substances, petroleum (high octane aviation gasoline) and factory machinery.

[59]: 129  Without Lend-Lease aid, Soviet Union's diminished post invasion economic base would not have produced adequate supplies of weaponry, other than focus on machine tool, foodstuff and consumer goods.

[59]: 128  The Soviet Union received shipments in war materials, military equipment and other supplies worth of $12.5 billion, about a quarter of the American Lend-Lease aid provided to other Allied countries.

[59]: 133–4 Prof. Dr. Albert L. Weeks concluded, "As to attempts to sum up the importance of those four-year-long shipments of Lend-Lease for the Russian victory on the Eastern Front in World War II, the jury is still out – that is, in any definitive sense of establishing exactly how crucial this aid was.

As part of this, Operation Shamil was executed, a plan whereby a group of Brandenburger commandos dressed up as Soviet NKVD troops to destabilise Maikop's defences and allow the 1st Panzer Army to enter the oil town with little opposition.

Manstein's counteroffensive, strengthened by a specially trained SS Panzer Corps equipped with Tiger tanks, opened on 20 February 1943 and fought its way from Poltava back into Kharkov in the third week of March, when the spring thaw intervened.

After the failure of the attempt to capture Stalingrad, Hitler had delegated planning authority for the upcoming campaign season to the German Army High Command and reinstated Heinz Guderian to a prominent role, this time as Inspector of Panzer Troops.

He knew that in the intervening six months the Soviet position at Kursk had been reinforced heavily with anti-tank guns, tank traps, landmines, barbed wire, trenches, pillboxes, artillery and mortars.

Advancing on either side of the upper Donets on a narrow corridor, the II SS Panzer Corps and the Großdeutschland Panzergrenadier divisions battled their way through minefields and over comparatively high ground towards Oboyan.

The diversion of the well-equipped Großdeutschland Division from Belgorod to Karachev could not counteract it, and the Wehrmacht began a withdrawal from Orel (retaken by the Red Army on 5 August 1943), falling back to the Hagen line in front of Bryansk.

The main problem for the Wehrmacht was that these defences had not yet been built; by the time Army Group South had evacuated eastern Ukraine and begun withdrawing across the Dnieper during September, the Soviet forces were hard behind them.

Along Army Group Centre's front, August 1943 saw this force pushed back from the Hagen line slowly, ceding comparatively little territory, but the loss of Bryansk, and more importantly Smolensk, on 25 September cost the Wehrmacht the keystone of the entire German defensive system.

Despite a ferocious attack at the Sinimäed Hills, Estonia, the Soviet Leningrad Front failed to break through the defence of the smaller, well-fortified army detachment "Narwa" in terrain not suitable for large-scale operations.

[110] The three Soviet fronts had altogether some 2.5 million men (including 78,556 soldiers of the 1st Polish Army); 6,250 tanks; 7,500 aircraft; 41,600 artillery pieces and mortars; 3,255 truck-mounted Katyusha rocket launchers, (nicknamed "Stalin Organs"); and 95,383 motor vehicles, many of which were manufactured in the United States.

[117] Dönitz and Schwerin von Krosigk attempted to negotiate an armistice with the Western Allies while continuing to resist the Soviet Army, but were eventually forced to accept an unconditional surrender on all fronts.

The Soviet invasion of Manchuria began on 8 August 1945, with an assault on the Japanese puppet states of Manchukuo and neighbouring Mengjiang; the greater offensive would eventually include northern Korea, southern Sakhalin, and the Kuril Islands.

[126] Memorandum for the President's Special Assistant Harry Hopkins, Washington, D.C., 10 August 1943: In World War II, Russia occupies a dominant position and is the decisive factor looking toward the defeat of the Axis in Europe.

After the war, following the Yalta conference agreements between the Allies, the German populations of East Prussia and Silesia were displaced to the west of the Oder–Neisse line, in what became one of the largest forced migrations of people in world history.

According to a summary, presented by Lieutenant General Roman Rudenko at the International Military Tribunal in Nuremberg, the property damage in the Soviet Union inflicted by the Axis invasion was estimated to a value of 679 billion rubles.

[citation needed] Hitler exercised tight control over the German war-effort, spending much of his time in his command bunkers (most notably at Rastenburg in East Prussia, at Vinnitsa in Ukraine, and under the garden of the Reich Chancellery in Berlin).

Stalin promoted some obscurantists like Grigory Kulik who opposed the mechanisation of the army and the production of tanks, but on the other hand purged the older commanders who had held their positions since the Russian Civil War of 1917–1922, and who had experience, but were deemed "politically unreliable".

[citation needed] ... Hitler's first defeats on the frontline outside Moscow drove him to endorse plans for the total extermination of the Jews, and almost simultaneously to openly intensify the anti-Slavic slogans of anti-Bolshevist and anti-Semitic propaganda.

This was particularly true for the territories of Western Ukraine, recently rejoined to the Soviet Union, where the anti-Polish and anti-Soviet Ukrainian nationalist underground hoped in vain to establish the "independent state", relying on German armed force.

As they retreated from Ukraine and Belarus in 1943–44, the German occupiers systematically applied a scorched earth policy, burning towns and cities, destroying infrastructure, and leaving civilians to starve or die of exposure.

The Soviets incrementally upgraded existing designs, and simplified and refined manufacturing processes to increase production, and were helped by a mass infusion of harder to produce goods such as aviation fuel, machine tools, trucks, and high-explosives from Lend-Lease, allowing them to concentrate on a few key industries.

The huge death toll was attributed to several factors, including brutal mistreatment of POWs and captured partisans, the large deficiency of food and medical supplies in Soviet territories, and atrocities committed mostly by the Germans against the civilian population.