149: The Isthmus Grind


In early 1940 Timoshenko and Zhukov would arrive, it was time for the Red Army to get serious.



Hello everyone and welcome to History of the Second World War Episode 149 - The Winter War Part 7 - The Isthmus Grind. This week a big thank you goes out to Monika and Simon for choosing to become a podcast member, you can find out more over at historyofthesecondworldwar.com/members. Over the last few episodes the podcast has looked at the fighting that was occurring north of Lake Ladoga, but south of the lake, and on the Karelian Isthmus the fighting would begin to rapidly escalate in intensity in late January 1940. The failures of Soviet attacks in the north just reinforced the fact that the decisive theater of the war would be the Isthmus, and the focus of both armies would be clearly on the Finnish defenses on the Isthmus. During these renewed attacks the Red Army would have a new commander and a new plan. As the war drug on the Finns were also running out of men and resources, and so the assistance of other nations was even more necessary, with the easiest possible avenue for that support being from its Nordic neighbor, Sweden.

Of all of the nations that could have sent meaningful aid to Finland during the war, Sweden was the best positioned to do so. With a long shared border, and generally aligned political goals, the two Nordic countries were a match to work together. Swedish leaders also liked the idea of Finland continuing to exist as a buffer state between Sweden and the Soviet Union. There was real concern that if Finland was incorporated into the Soviet Union an invasion of Sweden would follow, and it was this possibility that shaped Swedish military planning and preparations during the interwar years. During the 1920s and 1930s the most likely threat seemed to be either a Soviet invasion or an invasion by a Western Power, and so the plan was to mass most of Sweden’s defensive capabilities in southern Sweden to prevent amphibious landings along the coastline. Then when the Winter War started, Sweden found itself in an amazingly awkward and dangerous position. The basis for Swedish foreign policy remained complete and total neutrality, they advocated for a peace agreement to end the Winter War, but from a national political perspective they made it clear that Sweden remained neutral. But there were many threats to that neutrality, even outside of the Soviet Union. After the war started France and Britain had lengthy discussions, and formulated plans, about intervening on behalf of Finland, even if it meant war with the Soviet Union. But the best way to intervene would be to send troops and supplies through Norway and Sweden, but both of those nations were neutral. And if that did happen, and Sweden did not resist this transit of troops it was very likely that Germany would invade Sweden to protect it as a source for iron ore. Even the idea of Britain and France moving troops through Sweden might be enough to trigger a German invasion. And not to jump too far ahead, but this was a very reasonable concern for the Swedish leaders because that scenario I just described, a threat of France and Britain violating a nation’s neutrality and Germany invading just out of concern for the possibility, is exactly why Germany would invade Norway. All of these threats made it essential that Sweden maintain an official neutrality, but there were many instances of support for Finland among Swedish individuals and groups within society. This would result in the creation of the Swedish Volunteer Corps which would fight in Finland during the war. The Volunteer Corps would eventually number 8,260 men, although there were more applicants that were rejected. It is worth mentioning that there were volunteers from other nations as well, for example over 700 Norwegians, and 600 volunteers from Denmark, but for nations that were further away often the volunteers did not have time to reach Finland before the war ended. For example about 1,000 citizens of the United Kingdom volunteered and were actually on their way to Finland when the war ended. But the Swedes would always be by far the largest contingent, and their three battalions would be given a sector of front in northern Finland to defend, which allowed the Finnish troops that were responsible for this defense to be moved south for heavier fighting. As with any volunteer military group, the men who volunteered came from a variety of different backgrounds and joined for a variety of different reasons. Many were just seeking adventure, with one volunteer claiming that it was the childhood memories of the First World War and the adventure of the military life that caused him to join up. Others believed that they were protecting Sweden by fighting the spread of Communism into Finland. In January 1940 the Soviet government would lodge an official complaint to the Swedish government about the volunteer corps, but this did not cause any change within the government on its views about the Corps. The Swedish response would be that the government had not participated in organizing the unit or recruiting its volunteers and so it did not represent any violation of Swedish neutrality. In the end of the Swedish volunteer Corps did not chance the course of the war, but it would be a strong display of Nordic unity at a time when all four nations were under threat in their own ways.

We first covered some of the actions on the Karelian Isthmus back in episode 3 of this series before the narrative shifted to the various fighting in northern Finland. But to refresh your memory, the opening attacks of the war on the Isthmus had largely been failures for the Soviets. They had been able to push the Finnish defenders back into the Mannerheim line, but once the fighting reached the primary line of defenses it became very difficult for the Red Army troops to make meaningful headway against the Finns. The success of the defense led some Finnish leaders to start suggesting a counter attack on the Isthmus as early as December 11th, before the fighting even reached the primary line of resistance. Mannerheim believed these early proposals were premature and would not approve a counterattack until December 22nd, after the Soviet attack had started to bog down. The attack would take advantage of the fact that there was one Finnish division that had not yet been committed to the fighting, the 6th Division, which would be a primary participant in the attack. The general plan for the attack was a bold one, a double pincer attack that would attempt to isolate and destroy many of the Soviet troops facing Summa on the southern end of the Isthmus. The Sixth division would attack along the southern pincer while the 1st division would attack along the northern pincer. If everything went well 3 Soviet divisions would be cut off, and at the very lead it would completely destroy whatever the Soviet time table was for another major offensive effort. But there was a problem, the Finnish goals were completely disconnected from their abilities on this sector of the front. In the north Finnish attacks had been successful because they had taken advantage of Finnish strengths while preying on Soviet weaknesses, primarily around the much greater Finnish mobility and the spread out nature of the Soviet defenders. This would not be the case on the Isthmus where the sheer volume of troops on both sides made mobility and surprise impossible. Finnish intelligence also just was not good enough for the operation, they did not really know what was beyond the very first set of Soviet units, with no real ability to know what the Red Army had in reserve or where those reserves were positioned. There would also be smaller mistakes made, for example the 6th Division, when it was sent forward to prepare for the attack, would move forward too late and all at once which created essentially a traffic jam behind the Finnish front which meant that the attack would move forward with only a fraction of its expected forces at 6:30AM. Unfortunately for the Finnish troops, what they ran into was a solid wall of Soviet firepower. The large artillery advantage that the Soviet possessed on this area of the front meant that the attack was over just a few hours after it started after only advancing around 2 kilometers. It also did not help that the some of the Sixth Division’s units ran directly into a very large Soviet tank park, which they of course they were unable to really attack or destroy. In the north the 4th Division’s attack lasted a bit longer, but was only marginally more successful, ending at around 3PM. The 4th had had advanced slightly further, but not really in the correct direction, with the positioning of Soviet units and defenses forcing it to advance east and north instead of east and south according to plan. Once the two Finnish pincers were stopped it was impossible to restart the attack because Soviet reinforcements came streaming in from other areas of the Isthmus and from the rear. Overall the Finns would suffer 1,300 casualties in the attack, with roughly the same number of Soviet casualties. But maybe more importantly, it made it clear the Finnish leaders that at least on the Isthmus, the decisive theater, it was impossible to recapture any kind of initiative, and they were largely at the mercy of the attacks of the Red Army, and their best hope was that the Red Army commanders continued to make mistakes.


When the war started Soviet planning had been for a quick march to Helsinki through the Isthmus, and the plan was for the war to be over in a matter of weeks. By the end of December it was clear that this was going to be a much more challenging war than originally planned, and publicly this was blamed on things outside of the control of the Soviet Union, the Mannerheim Line was stronger than the Maginot Line, thousands of capitalist pilots and volunteers had arrived in Finland, the terrain was horrible, you know that kind of stuff. But privately most of the blame fell on the Soviet leaders in charge of the war, which were from the Leningrad Military District. A reorganization was in order, and it would take place during the first week of January when the Leningrad Military District was renamed to the “Northwestern Front” and a new commander was brought it, Semyon Konstantinovich Timoshenko. Like many other Red Army leaders who had survived the purges, Timoshenko was a Civil War hero, having led a cavalry unit in the 1st Cavalry Army and forming a close personal bond with Stalin when they both found themselves in Tsaritsyn, later renamed Stalingrad, when they were fighting the White forces in southern Russia. Due to his connections with Stalin, Timoshenko was able to sideline all of the other party leaders that had been in control of the war up to this point in the conflict, and he brought with him a very bloody view of what would be required to win the war. He also brought with him his Chief of Staff, a man we have already encountered on the podcast due to his victories in Mongolia, Georgi Zhukov. The combination of Timoshenko and Zhukov would bring a much greater grasp of military planning and execution to the Red Army forces fighting the Winter War, and the reorganization would begin almost immediately. Many of the first changes were administrative, for example on the Karelian Isthmus the forces were divided into two corps so that they could focus on their own objectives. More troops were also brought onto the Isthmus with several additional divisions brought into the line behind those troops that were already present. The southern Corps under the command of Meretskov would now have at its disposal 9 infantry division, five tank brigades, a machine gun division, and enough artillery to have 80 guns per linear mile of front. These resources would now be used slightly differently than before, and they would begin what could best be described as a slow grind forward. Using their artillery and tanks the forces would begin just shoving through the Mannerheim line, with the goal of simply overwhelming each individual Finnish position regardless of losses. Fresh troops and vehicles would just continue forward until the Finnish resistance collapsed. An important part of this were large shipments of tanks which were brought in, including new KV heavy tanks which were much more powerful than anything that the Finns had seen up to that point in the war, including a large 76.2mm gun. Tanks were also to be used differently, instead of charging ahead of their infantry and artillery they would instead use their firepower to assist the infantry forward, with the infantry sticking with the tanks to provide them protection from the Finnish anti-tank tactics that had seen so much success in earlier fighting. This was probably the most important change made during this time, with a firm emphasis on the importance of combined armed tactics and every arm of the Army working together in unison to better utilize their individual strengths and cover for the weakness of others. In retrospect this seems like a simple subject, but it was new to the Soviet forces in Finland and it would make a tremendous amount of difference in the final stages of the war.

When Timoshenko took over command, one thing that would rapidly become clear is that he was much better prepared to take advantage of the strengths of the Red Army. He wanted to focus on artillery bombardment over the following days, to soften up the Finns for the attack. Then for 10 days the artillery and bombardment from the air would be brought up in intensity with goal of pushing through the Finnish defenses by February 11th. For long time listeners, this very long bombardment might feel familiar, as it was very reminescent of the week long bombardments from the First World War. The attacks that followed those bombardments would largely be failures, but the Red Army in Finland in early 1940 had one very key advantage, the Finnish forces were largely already committed to the front, there were no large concentrations of reserves which were always present on the Western Front from 1914-1917. And the Finnish forces were also not accustomed to such artillery, and every day after February 1st would see the intensity of Soviet artillery fire and air attack increase, with nothing that the Finns could do, they were completely unable to respond. The strong Finnish bunkers were not necessarily damaged themselves, but everything around them would be destroyed. Trenches, telephone cables, smaller defenses, all destroyed, any movement by troops between the various positions, impossible. During these days, every day attacks would be launched, only after massive bombardments and always in almost overwhelming force. In some cases there would be 100 tanks or more leading these attacks, and they would act as a steamroller, pushing forward with attacks multiple times per day regardless of casualties sustained. Finally the Soviets were taking advantage of their massive numerical superiority by constantly feeding fresh troops into the attacks, even though multiple attacks were occurring every day. The Finns were simply overwhelmed, mentally by day after day of constant artillery fire, physically by the inability to sleep through all of the explosions and fighting, and numerically by the Red Army forces. There were many Soviet casualties during these days, but Timoshenko had been planning for that, he knew that to push through the Finnish defenses would require a certain price in blood, but he was determined that if that price was to be paid the attack would be successful. Mannerheim had a single reserve division, the 5th, at his disposal, but he faced the problem that would so often be faced by outnumbered defenders, where to use this division. He could split it up into smaller groups and send them forward to reinforce some of the sectors under attack, but by doing so he would lose his ability to react to a Soviet breakthrough. But if he did not commit it early enough he risks the Soviets achieving a breakthrough that could not be stopped. The problem was that the Soviets were attacking along the entire front, from Taipale in the north all the way to the Gulf of Finland in the south. In each sector the fighting was different, in the center and south the Soviets were attacking directly into the strongest positions of the Mannerheim Line, and somehow the troops there continued to hold. In the north there was savage fighting around the coastal batteries on the shores of Lake Ladoga, with large Soviet units actually uses the frozen Lake Ladoga to expand their attack frontage. But while the details differed, the general story all along the line was the same, unless something changed, whether through Finnish action, Soviet mistakes, or some kind of external factor, by February 12th it was starting to look like it was only a matter of time before the Finnish defenders were simply ground down to nothing.

If left alone to fight the Soviet Union, Finland knew that it had little chance to win a war against the Soviet Union. There was always hope that help would arrive from other nations once the war started, but unfortunately there was another war going on by the time of the Soviet invasion. But this did not prevent France and Britain from at least considering sending help to Finland. There were three major obstacles that stood in the way of this help arriving, geography, the simple lack of resources, and the chance of war with the Soviet Union. The first problem is the easiest do discuss, when trying to extend meaningful military aid to Finland, geography was a problem, especially while the two nations were at war with Germany. The Baltic could not be used, and this meant that any military aid needed to be sent to northern Finland, but the ports in northern Finland would be overwhelmed by the requirements that would be placed upon them to support a major British and French military effort. The size of the largest of the plans would have involved 100,000 British, 50,000 French, and considerable aviation resources being sent to Finland, which would have required a constant flow of supplies. The other option was to send the forces through Norway and Sweden starting at the Norwegian port of Narvik, but both nations were neutral, and so moving troops through the two nations would have represented a violation of that neutrality, which both Norway and Sweden were not big fans of this idea, and the British and French knew that they would not just allow it to happen without protests. Both nations were concerned about the possibility of a German invasion of their neutrality was violated and they did not resist, the British and French planned to give them an out on a technicality, saying that they would label the forces sent just as a major force of volunteers, but that was extremely flimsy. The second major obstacle was the fact that this type of operation would result in the Soviet Union joining in the war against Britain and France. In hindsight, even discussing bringing the Soviet Union into the war against Germany would have been complete and total madness by Britain and France. But at the time it was seriously discussed both around helping Finland as well as bombing Soviet oil fields around Baku to stop the export of that oil to Germany, a plan that do not worry we will discuss in much greater detail in a later episode. For this episode, the most important thing to say is that the idea of going to war with the Soviet Union was not a consideration that prevented detailed British and French planning for how they could send help to Finland and the help that could be sent. The final major obstacle was simply gathering up the required forces that would be sent. Both Britain and France were ramping up their military productions with the goal of defending against the expected German attack into France, and so it was hard to bring together enough forces to send to Finland’s aid. This did not hamper the desire for the fighting to shift into Northern Europe though, and the French were always open to discuss any actions that might cause the fighting to not happen on French soil. Even with these three obstacles, detailed discussions and planning did occur in the Supreme War Council in early January with both a large and small plan discussed. In the larger plan the British and French governments would openly declare their intention to send military assistance to Finland, with the League of Nations as the cause, and they would demand Norway and Sweden let them through, the Norwegian port of Narvik would be used along with the Swedish port of Lulea, which would you believe it were the two primary ports used to export Swedish Iron Ore to Germany! What a coincidence! This large plan was never going to happen, and instead the Small plan was more likely. But this smaller plan would see the number of troops ramped up as it was felt that the original 30,000 men were not enough to make the difference required and eventually it would increase to 150,000. Where were these men going to come from? Nobody really knew. And regardless, it required that Norway and Sweden let them transit their countries, which they were never going to do. And to add some additional fillings into this impossible sandwich, the Finnish government was not even brought into these discussions until February, after many decisions had already been made. By that point the Finnish government was already discussing how to end the war with the Soviets through negotiations, even at the cost of territory. And while they saw the British and French plan as a possible bargaining chip in those negotiations, their priority was still to get into direct negotiations with the Soviet Union and get out of the war. Fortunately for the British and French, and their later fates in the Second World War, they would not be able to send aid to Finland before those negotiations started, which prevented them from making the unbelievable blunder of entering into a war with the Soviet Union, and possibly causing Germany and the Soviet Union to work closely together militarily against the two nations for any period of time.