It advanced towards the Terek river, but was eventually forced to withdraw by the winter of 1942/43, concurrent with the decisive defeat of Army Group B in the Battle of Stalingrad.
Additionally, the implementation of the plan was not helped by the fact that Halder's intrigue to replace Manstein had resulted in the appointment of Georg von Sodenstern as chief of staff of Army Group A.
A conservative-minded planner, von Sodenstern had initially been selected by Halder precisely because he opposed the Manstein Plan, and was now left to oversee its realization.
As a result, the leadership of Panzer Group Kleist had a strong incentive during the campaign for single-minded and daring operations to preserve their organizational autonomy.
[3]: 106 Within days of the beginning of the campaign, the troops of Army Group A achieved what one of the army group's staff officers, Günther Blumentritt, would later refer to as a "three-fold miracle": The Allied air forces failed to attack the lengthy tank columns that were stuck for hours on end in traffic jams trying to cross the Ardennes, the Germans succeeded with high speed and low casualties to cross the Meuse river with the breakthrough in the Battle of Sedan, and the German tank divisions finally won a stunning victory in what was at times a more than reckless advance towards the channel coast, dangerously abandoning the cover of the German thrust's flank against a potential Allied counterattack that never materialized.[3]: 2f.
The leader of the panzer group, Ewald von Kleist, found himself in the difficult situation of mediating between his superior army group and his subordinate corps commanders; Kleist had initially covered Reinhardt's autonomous actions but was forced on 17 May to give a definitive holding order to Guderian, as Hitler personally had decreed a deceleration of the armored advance.
Due to a coincidence, Hitler happened to be present at Army Group A headquarters on 24 May, and overruled Brauchitsch's instructions, implementing instead the "halting order".
[4]: 318 After the Allied evacuation at Dunkirk, Army Group A tuned southeast and advanced in the general direction of the Vosges mountains and the France–Switzerland border, thus encircling the static French forces positioned along the Maginot Line.
The strategic idea cherished by Hitler was to hold the Kuban bridgehead long enough to commence a major offensive in summer of 1943 in order to recapture the Maykop oil fields.
After a directive by Stavka had reached the North Caucasus Front on 16 March, the Soviet forces initially were placed on defense to prepare offensive operations, to begin in April.
After Georgy Zhukov had personally inspected the Soviet lines along the North Caucasus Front's field armies, he issued orders on 17 April to temporarily cease offensive operations.
The ground forces assigned to this defensive task were entirely insufficient, and were further hindered in their preparations by a general Soviet aerial supremacy over the southern sectors of the frontline.
[14]: 453 After the evacuation of the Kuban bridgehead had been completed, 17th Army was tasked with the defense of the Crimean peninsula, dubbed in Nazi parlance as "Fortress Crimea".
Hitler's view clashed with those of Ion Antonescu, the autocrat of Romania, whose troops made up the majority of 17th Army and who doubted the prospects of defending the isolated peninsula against strong Soviet formations and who feared similar Romanian casualties in Crimea as had been suffered at Stalingrad, which he believed to be politically unsustainable for his government.
This uncertainty turned into impossibility when Erich von Manstein of Army Group South demanded the evacuation of the Nikopol bridgehead in January 1944, thus removing the jumping-off point from which the relief of Crimea would have had to be launched.
Manstein's demands to evacuate the 17th Army to re-insert it into the line on the mainland were rejected by Hitler, who insisted on the continued defense of the Crimean peninsula.
Attack across the Syvash bay by forces of the 4th Ukrainian Front in early November could still be mostly deflected by the German defenders, though minor territorial losses had to be accepted.
The sole reserve of the 17th Army was the Mountain Regiment Crimea (Gebirgsjägerregiment Krim), and its armored forces were limited to 45 assault guns that were to be supported in anti-tank operations by elements of the 9th Flak Division.
Kleist ordered a counterattack to be launched by IV Corps on 8 February, but this counter-thrust proved entirely ineffective due to Soviet ground and air superiority and adverse weather conditions.
On 10 February, Army Group A inquired to OKH about an urgent large-scale retreat to the Bug—Inhul position, which would shortened its frontline from 320 to 200 km and allowed to place three to four divisions in reserve for additional operations.
But as the HQ of Army Group A at Mykolaiv waited for OKH's response, the Soviets launched another two-pronged attack against Krivoi Rog to trap LVII Panzer Corps.
While this measure expanded the frontline of Army Group A by another 110 kilometers, it offered the chance to coordinate the defensive strategy along the entire southern sector of the Eastern Front.
However, Hitler's repeated interventions in military decisionmaking again prevented a necessary withdrawal, as the LII Corps was ordered to stand its ground southeast of Kirovograd while Stavka was already preparing the next offensive step against the beleaguered Germans.
[14]: 474–477 Army Group A inflicted significant setbacks to the 3rd and 4th Ukrainian Fronts, causing disappointment in the ranks of Stavka about the results of the Soviet winter operations of 1943/44.
The 3rd Ukrainian Front under Rodion Malinovsky was repurposed to break for the significantly reduced ambition to breach the German defenses on the lower Inhulets river line and to capture the major town of Mykolaiv (where Army Group A had established its HQ).
OKH suspected that the southern front sector, with the weakened Army Groups South and A in exposed position, would be the focus of Soviet spring operations in 1944.
6th Army stood exposed, as only its left wing was west of the Inhul, the center along the Inhulets and the rightmost elements still on parts of the Dniepr line.
This delayed withdrawal robbed Army Group A of any time it could have used to build preliminary defensive lines, and placed additional pressure by the Soviets against the retreating Germans.
Additionally, the war had now reached the core territory of the Kingdom of Romania, rendering the political future of Hitler's most important ally, Ion Antonescu, as well as the continued support of the German Army Group A by its Romanian divisions, more than questionable.
Army Group Vistula was to be inserted in the northern sector of the mainland of the Eastern Front, to prevent the Soviet breakthrough towards Danzig and Posen.