At the beginning of Fall Blau the Caucasus was not very well defended, as the rapid advance might show.
The army was approaching and the Luftwaffe had a large bomber and fighter force on intact forward airfields.
The biggest flaw in all of this is that the speculation "take Baku – get oil" was not even an option at the time. As the Germans knew in the First World War, and as the Germans should have known in the second. They did know on the level of military specialist planners. They did not want to know in the higher strata.
Hitler had almost certainly not read the March 1941 report by Lieutenant General Hermann von Hanneken of the War Economy and Armaments Office, which was appended to a letter sent by Generalfeldmarschall (Field Marshal) Wilhelm Keitel to the High Command of the Army (OKH). This report warned that, even if the Caucasus oilfields could be captured intact, very little oil (only ten thousand tons per month) could be carried overland to Germany. Moreover, even if the Black Sea could be made safe for shipping, there would be no ships available for the transport of Caucasus oil up the Danube because the Danube river tankers were already working to capacity transporting Rumanian oil.14The only remaining route was across the Black Sea, through the Dardanelles, and on to Mediterranean ports. Accordingly, the report concluded, "the opening of the sea routes and the security of the tankers in the Black Sea is the prerequisite for the use of Russian supply sources in sufficient quantity to support the further continuation of the war." Clearly, to attain this prerequisite was virtually impossible by early 1942; the Germans would have had to wipe out the powerful Soviet Black Sea Fleet (which still had, according to Groladmiral Raeder, "naval supremacy . .. [allowing] great freedom of movement") and to eliminate British air and sea power from the eastern Mediterranean.
The actual defences at Baku are not only for that rather irrelevant.
Even Maikop, the nearest oilfield, was –as the crow flies– 335 kilometers away from Rostov, where List's armies stood ready for their drive south. Grozny was almost twice that distance, and Baku, Hitler's ultimate goal, was no less than 1,200 kilometers away. The latter, to illustrate the significance of these distances, was as far from Rostov as that city was from the Polish-Soviet border.
And then even Maikop did not produce any significant amount of any oil for the Germans! They had taken the fields, they held it for some time, and the nearest oil-field was of no use, practically. They denied the Soviets access to it and they could have dealt a significant blow to Baku. Without capturing it. Wells are relatively simple compared to refineries. But to get usable petrol for use in the Eastern theatre one would have needed both. While both are easy to destroy, it takes time to just put out for example burning wells, or in the Soviet case even redillling much a new, since they plugged them up, and then again longer to get the complex refineries up again.
Schlicht was right: Gdring's grasp of matters relating to oil production was extremely weak. For instance, two months later, on 21 November, he presided over an oil conference in Berlin. Maikop, which had yet
to produce oil for Axis troops (and never would, except a few dribbles), remained at the forefront of his mind. "I'm fed up," he exclaimed. "Months have passed since we captured the first oil wells, yet we still aren't getting any benefit." He astounded his audience of technical experts when, referring to the concrete plugs dropped down the bores, he naively demanded to know: "Can'tyou just drill them out with something like a gigantic corkscrew?"
–– Too Little, too late.
Until August 42 the forces at Baku were extremely weak, except for air-defence. Which the Soviets concentrated in Leningrad, Moscow – and Baku! But in September reinforcements of all kinds rolled into Baku. And as in absolute parallel the German forces deteriorated. Not many comparisons in sheer numbers would make any more sense than speculating of how many ghost units would be needed to do the by now impossible.
–– Joel S A Hayward: "Too Little, Too Late: An Analysis of Hitler's Failure in August 1942 to Damage Soviet Oil Production, The Journal of Military History, July 2000. (PDF) Also: Joel Hayward: "Hitler's Quest for Oil: the Impact of Economic Considerations on Military Strategy, 1941–42", Journal of Strategic Studies, Vol.18, No.4 (December 1995), pp.94–135. (PDF)
Not one oilfield or one refinery – for the Western oilfields small anyway – was captured intact. While wells could have been made operational relatively quickly, in theory, the necessary refineries would take inevitably longer, despite nearly 11000 specialists available on the German side.
Another factor in Hitler’s zero-sum calculus that redirected the war in the East towards the Caucasus was the Allied–Soviet occupation of Iran in August–September 1941. Soon afterwards, the British began establishing a land route through Iran known as the Persian Corridor to supply Lend Lease aid to the Soviet Union. By November 1941, the first British-built aircraft and tanks began arriving at Baku in the Caucasus and by early 1942 the US Army also joined in the effort. Since Soviet industry was still unable to replace all the material losses of 1941, Allied Lend Lease helped to bridge the gap until Soviet domestic production could outstrip Germany’s.
Consequently, cutting off the Persian Corridor was an important secondary objective that could be fulfilled by a German occupation of the Transcaucasus region. Deprived of both oil and Allied materiel, Hitler expected the Soviet war effort to wither. More quixotically, he believed that once the Caucasus was occupied, it might be possible to send German expeditionary forces into Iraq and Iran to threaten the British position in the Middle East.
Hitler promised that both the Romanian mountain corps and three Italian mountain divisions would be committed to reinforce Heeresgruppe A by mid-August, enabling an equally rapid thrust to seize the Caucasian mountain passes and begin clearing the Black Sea coast. Edelweiss also made extensive provision for the use of German special forces to seize or sabotage key targets and Hitler authorised Heeresgruppe A to consider using airborne troops if feasible. However, the plan did not detail how German forces would reach distant Baku or what the Luftwaffe was expected to accomplish beyond supporting the army and attacking coastal shipping. At best, Edelweiss was an unfinished sketch, vulnerable to diverging objectives, limited knowledge of the terrain and the Führer’s whimsy.
Von Kleist’s panzers raced into the Caucasus with only a hazy idea about the nature of the terrain and weather they would be up against. German maps of the region were decades out of date and many bridges or other critical terrain were not properly marked. Roads that appeared trafficable for vehicles often turned out to be mule paths. Indeed, the Germans were not even sure about the exact location of their primary objectives – the oilfields – and would be shocked to discover that most of the oil wells at Maikop were not actually in the city or even centralised in one location. Again and again, the Germans were forced to feel their way blindly ahead, looking for trafficable routes and river crossings in a land of which they were mainly ignorant. Furthermore, the amount of distance that needed to be covered to reach the oilfields was staggering: 330km to Maikop, 750km to Grozny and 1,285km to Baku. During Operation Barbarossa, some German panzer units had advanced over 1,000km in five months, but Hitler was asking Heeresgruppe A to accomplish a similar level of effort in just three months before winter weather arrived.
An anti-tank strongpoint was established at the village of Khulkhuta, 120km west of Astrakhan. The Soviet 28th Army held the approaches to the city with the 34th Guards Rifle Division and mounted raids against the German outposts. Between 13 and 14 September, four armoured cars from the Kradschützen-Bataillon 165 conducted a long-range patrol which reached the train station at Zenzeli and briefly interfered with rail traffic on the Astrakhan–Kizlyar line, then retreated. Henrici did not know it, but between August and October 1942 some 16,000 rail cars carrying fuel moved north along this line from Baku – a total of about 150,000 tons of crude oil. For the next few months, Henrici conducted his screening operation in the Kalmyk Steppe, occasionally sparring with the 28th Army.
By early October, it was obvious that von Kleist’s offensive had stalled and that his army would not get to Grozny anytime soon. Stavka also realised that the defences on the Terek were sufficient to keep the Germans out of Grozny and sent its remaining reserves to the Stalingrad Front. Hitler ordered the Luftwaffe to set the oilfields in Grozny ablaze and Fliegerkorps IV mounted two large-scale raids on 10 and 12 October; although these inflicted serious damage, the effort was suspended.
–– Robert Forczyk & Steve Noon: "The Caucasus 1942–43: Kleist's Race for Oil", Osprey: London, 2015.
And Toprani even argues that in 1941 it was already game over:
The German summer offensive against the Soviet Union in 1942, Case Blue, is one of the most famous campaigns in history thanks to the Battle of Stalingrad. Although historians agree that the offensive’s aim was control of the Caucasian oilfields, there is a widespread misconception that Baku was the main objective. German ambitions were in fact rather modest—the primary objectives were the smaller and more accessible oilfields of Maikop and Grozny. The Germans were also just as determined to deny the Soviets access to Caucasian oil by severing transit along the Volga as they were to secure the oil for themselves.
–– by Anand Toprani: “The First War for Oil: The Caucasus, German Strategy, and the Turning Point of the War on the Eastern Front, 1942”, The Journal of Military History, 80:3 (July 2016): 815–54
Some numbers to illustrate the difficulties encountered in refining and transportation – including plans on what to do with Iranian and Irqi oilfields after a German capture in a nazi-post-war world in:
–– Anand Tropani: "Germany’s Answer to Standard Oil: The Continental Oil Company and Nazi Grand Strategy, 1940–1942", Journal of Strategic Studies, 37:6–7, 949–973, DOI: 10.1080/01402390.2014.933317
And while Soviet oil was incredibly important for the Soviet war effort, one shouldn't discount other sources for oil. American delivery and those originating from Persia have to be included for perspective between 1939 and 45. And that Caucasus oil was different than what Germans had experience from their own tiny fields or those in Romania, that any potentially captured refinery produced a different set of petrochemicals needed by the Germans, the Soviet having themselves difficulty with transport under more favourable conditions – and finally the Soviets not only destroying refineries, but dismantling and transporting them off:
In fact, due to the developments shown above, the Soviet oil industry was nearly stagnating in absolute terms on the eve of the Second World War, and the share of oil in total energy consumption was declining further.
To avoid, or at least delay, a German attack, Stalin ensured the punctual delivery of raw materials requested by Hitler as part of the Molotov– Ribbentrop Pact of 1939, while the German government, whenever possible, delayed or postponed the delivery of the goods it was exchanging in the barter deal, which mostly consisted of advanced armament and industrial equipment. US economist Robert Campbell holds that while the Soviet Union continued to ship vast quantities of refined and semi-finished petrol products to Germany, the USSR became a net importer of oil. In particular, American oil companies were more than willing to send oil to the Soviets to enlarge their profits—even though they must have been aware that these oil imports were mostly forwarded to the German Wehrmacht.
However, not all of the oil was exported or used up; the Soviet leadership had begun to stockpile increasing amounts of oil supplies as a precaution for war. While there is no doubt the Soviet Union was caught by surprise when the Germans attacked, Moscow had taken some contingency measures to prepare for a confrontation. Nevertheless, once the war started, the stockpiled oil reserves proved insufficient and were quickly exhausted. The situation was further worsened by a lack of supply lines and inadequate transportation capacities; the fuel supply situation of the Soviet economy and for countless military units was disastrous at the beginning of the war.
Despite these severe repercussions, the Baku oil district increased its oil production in 1941. However, as thousands of oilmen were recruited to fight, the production of equipment was nearly closed down, and parts of the machinery had to be handed over to the defense and armament industry, it soon became clear that Baku was unable to continue production on such a high level. The oil produced at Baku would not suffice to win the war.50 To make matters worse, Hitler made no secret of his aim to seize the Caucasian oil wells. After the German offensive had been halted and repulsed in the Battle of Moscow in early 1942, the Wehrmacht concentrated its efforts on the southwestern oil fields. Although German troops never reached Baku, their advance towards the Caucasus did affect the Soviet oil branch in several ways: first, investments in the Caucasian oil industry were reduced to a minimum, and in case the Germans might take control, oil wells of minor importance were shut down and concreted over. The latter action, in particular, set back oil production by years.52 Second, the Soviet Union’s State Defense Committee (GKO) decided to evacuate personnel and machinery from Baku. Huge parts of the remaining drilling equipment, pipelines that were not usable during the war, and several refineries were dismantled and moved to safer grounds. First to benefit from this decision was the only other region within the Soviet Union known for its vast oil reserves—“Second Baku.”
When the Wehrmacht reached the Volga in the summer of 1942 — until then the main transport route for Caucasian petrochemicals on the way to the northern industrial centers — the fuel supply became more complicated. It was now too risky to ship oil from Baku up the Volga River within sight of the Germans, who would have been able to snatch this low-hanging fruit. In addition to costly detours through Kazakhstan and Siberia to bring fuel to its consumers, oil tanks near the Caucasian wellheads were overflowing as a result of the lack of transport capacity; additional oil wells had to be taken out of service. Members of the GKO saw their previous decision substantiated, which made them order further equipment transfers to the “Second Baku.” From then on, “all possible steps to accelerate and increase oil production in the eastern oil regions” had to be taken, including “mass propaganda work” that would explain to all workers “the importance and significance for the country and the front of the transfer of […] equipment and staff.”
While the evacuation order was a heavy blow to the Caucasian oil industry, the Volga-Ural industry saw its fortunes change, even though its output was nowhere near sufficient to compensate for the collapse of the former.56 In 1943, Soviet oil production reached its lowest point since the late 1920s at a mere 18 million tons — a decline of almost 50 percent in comparison to 1941. Evidence for the damage to Baku’s oil wells can be seen in the fact that the Caucasian oil industry failed to achieve its former production peak until the collapse of the Soviet Union. But for the first time since its discovery, creating a mighty oil base in the eastern part of the country was—not only rhetorically—both a reality and high priority in the USSR’s economic planning.
In addition to Soviet efforts, foreign assistance was invaluable for the development of “Second Baku,” especially for its refining capacity: the Lend-Lease arrangement, initiated in March 1941 by the US to assist Allied forces in their war with Germany, was extended eastwards shortly after the Soviet Union joined the Anti-Hitler coalition during the second half of 1941. Thereafter, weapons and defense-related equipment were sent by the Western Allies to support Soviet resistance against German aggression. Although petroleum-related equipment made up only a small share of these aid deliveries, it consisted of modern exploration and drilling instruments, oil storage tanks, and pipes and compressors that were no longer being produced, having been halted in favor of armament. Perhaps even more importantly, six entire refining facilities, urgently needed to process Volga-Ural oil, were disassembled in the US and shipped to the USSR, along with further refining equipment. Up to this point, Soviet engineers had experienced immense difficulties in producing valuable petrochemicals in the region, owing to the extraordinarily high sulfur content and the lack of appropriate technology.
–– Jeronim Perovic: "Cold War Energy A Transnational History of Soviet Oil and Gas", PalGrave MacMillan, Cham, 2016.