116: Danzig and Army Modlin


We begin our story of the defense of Poland by starting in the north with the hopeless defense of Danzig and the Baltic sea coast before moving further east to Army Modlin north of Warsaw.


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  • Appeasement: Chamberlain, Hitler, Churchill and the Road to War by Tim Bouverie
  • The Origins of the Second World War: An International Perspective Edited by Frank McDonough
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  • The Foreign Policy of Jozef Pilsudski and Jozef Beck, 1926-1939: Misconceptions and Interpretations by Anna M. Cienciala
  • The French Government and the Danzig Crisis: The Italian Dimension by P.R. Stafford
  • Reflections from Rumania and Beyond: Marshal Smigly-Rydz in Exile by Stanley S. Seidner
  • Macht Arbeit Frei? Chapter: The War against Poland and the Beginning of German Economic Policy in the Occupied Territory by Witold Wojciech Medykowski
  • Poland Between the Wars, 1918-1939 Edited by Peter D. Stachura
  • Poland’s Preparation for World War Two by Michael Alfred Peszke
  • The Rebirth and Progress of the Polish Military During the Interwar Years by Jacek Czarnecki
  • Case White: The Invasion of Poland 1939 by Rober Forczyk
  • Poland 1939: The Outbreak of World War II by Roger Moorhouse
  • The Eastern Pact, 1933-1935: A Last Attempt at European Co-operation by Lisanne Radice (1977)
  • The Lights that Failed: European International History 1919-1933 by Zara Steiner
  • Agreement of Mutual Assistance between the United Kingdom and Poland, August 25, 1939.
  • Blitzkrieg Unleashed by Richard Hargreaves
  • The Great Powers and Poland: From Versailles to Yalta by Jan Karski
  • The History of the Panzerwaffe Volume 1: 1939-42 by Thomas Anderson
  • September Storm: The German Invasion of Poland by Gordon Rottman & Stephen Andrew
  • Britain and Poland, 1939-1943: The Betrayed Ally by Anita J. Prazmowska
  • March 1939: The British Guarantee to Poland - A Study in the Continuity of British Foreign Policy by Simon Newman (1976)
  • Poland 1939: The birth of Blitzkrieg by Steven J. Zaloga
  • Reflections from Rumania and Beyond: Marshal Smigly-Rydz in Exile by Stanley S. Seidner
  • Documents on German Foreign Policy 1918-1945
  • The British War Blue Book: Documents Concerning German-Polish Relations and the Outbreak of Hostilities Between Great Britain and Germany on September 3, 1939
  • The French Yellow Book: Diplomatic Documents (1938-1939)
  • Documents on German Foreign Policy 1918-1945 - Series D Volumn IV, VII
  • British Cabinet Papers - CAB 55/19/15, CAB 65/1/1-65/1/31, CAB 65/3/1-65/3/14, CAB 66/1/38-39, CAB 66/2/20


Hello everyone and welcome to History of the Second World War - The September Campaign Pt. 8 - Danzig and Army Group Modlin. This week a big thank you goes out to Michael and Keith for choosing to support the podcast by becoming a member. You can find out more about becoming a member over at historyofthesecondworldwar.com/members. During this episode we are going to be discussing the events of the first roughly 5 days of the German invasion of Poland in two important sectors. The first will be in the areas around and inside of Danzig, the Free City on the Baltic Sea adjacent to both the Polish Corridor and East Prussia. It was also completely indefensible without the grand scheme of how the Polish military leaders believed a German invasion would develop. It was almost inevitable that any forces placed in and around Danzig would be cut off from assistance by a German attack across the central or southern areas of the Polish corridor. The other area that we will focus on today will be the area of the border defended by Army Group Modlin, which was positioned between the southern border of East Prussia and the Polish capital of Warsaw. This was one of the most important areas for Polish defense because it was only about 100 kilometers between the border and Warsaw. It would be in this region that the Polish military had the least margin of error due to the general importance of Warsaw to the general functioning of the Polish military effort. Just as in every area of the fighting in Poland during the first few days of the invasion in both of these areas there was a mix of surprisingly stout Polish defense and almost completely unopposed German advances.

We start with was almost certainly the most hopeless situation for the Polish military, Danzig and the Baltic sea coast. As we discussed back in episode 111 the general belief among Polish military and political leaders was that attempting to defend the Polish Corridor, and especially the areas furthest to the north was a lost cause. With all of the other areas that had to be defended, and which were more important to national defense, there was just no way that the Polish army could put enough troops in the corridor to mount a serious defense. At its widest the corridor was only around 100 kilometers from the Western German border to the Eastern German Border, but there were political challenges to just ceding the corridor, with the general concern being that if Poland did not defend the area Germany might just invade, occupy it, and then sue for peace without really engaging with the Polish military in a meaningful way. With the necessity of defending the corridor, two Polish military formations would be established, with the Pomorze army stationed in the south and the Land Coastal Command guarding the northern areas of the corridor and the Baltic coast. The Pomorze Army will be the topic for our next episode, and today we will focus primarily on the forces that were grouped under the Land Coastal Command. Within the Land Coastal Command were 14,000 men, most of which had only arrived in their units in the days before September 1. The Five battalions of reservists would augment the 2 naval infantry battalions that were already in the area to form two Naval Rifle regiments. The two regiments were not well equipped with heavy weapons, with a distinct lack of artillery when compared to other Polish army units further south. One of the important reasons for this was that these units were also expected to defend the coastal areas as long as possible, with very little hope of survival. The nearest Polish forces were as much as 50 kilometers to their south, and it was expected that a vastly superior German force would make Danzig one of their very first targets in an upcoming conflict. On the German side the focus of their plans was strictly on capturing Danzig and establishing a secure land link across the Polish corridor. If Polish defenders remained on the coast they were of little concern, and the stretch of coastline that the occupied had little real strategic value. Because of this the forces designated to capture Gdynia and the coastal areas was not the best equipped or trained, and was clearly a second tier formation under the command of Leuitenant General Leonhard Kaupisch.

Near Danzig one of the most important areas was the military depot that had been built at Westerplatte. They had put some work into fortifying the area to make it more defensible, and unlike much of the other areas in Danzig, it was an area where Poland had been given full control which allowed them to establish and provision the military depot. Interestingly, they had been given this control due to the importance of Westerplatte as an area where military goods were offloaded from abroad and then transported into Poland. After 1938 the Poles had put even greater effort into reinforcing their position and treating it as the Polish bastion in the city. There were 210 soldiers within the fortifications which by the start of the war consisted of barbed wire entanglements, seven bunkers, trenches, and earthworks. They were also provided with 4 mortars, one field guns, and two anti-tank guns. The geography of the area favored the defenders, with the Polish depot at the end of a peninsula which was as narrow as 250m. The primary fortifications were also in a wooded area which gave them some more cover from German observation and attack. On August 31, the commander of the Major Sucharski would be informed that there would be no further reinforcements given to him, and he could expect to not receive any further assistance after a German attack. It was well known to the Germans that this would be an important position that they would probably have to assault in the opening hours of the attack if they wanted to fully control Danzig, and so they would plan to provide fire support for a ground attack from the pre-dreadnought battleship the Schleswig-Holstein. The Schleswig-Holstein was an old ship, launched in 1906 as one of the last pre-dreadnoughts built by the Imperial German Navy during that period. The ship had originally been decommissioned in 1917 before being turned into a floating barracks. It was partially due to its decommissioned status that it was allowed to survive the post-war peace settlements that saw the rest of the German Navy surrendered to the British. By 1918 it was felt that an old pre-dreadnought like the Schleswig-Holstein was not really a threat to the other navies around Europe. But at 4:47AM on September 1st the ship, and most importantly its guns was certainly a threat to the defenders on the Westerplatte. Over the course of 7 minutes the ship would fire 8 28cm or 11 inch shells and 39 15cm or 6 inch shells at the defenders. Mistakes were made though, and because the ship was so close to the target, just around 500 meters, some of the shells did not even arm in time to explode, and those that did explode at the proper moment did not do very much damage. In fact in the entire 7 minute barrage the total number of Polish casualties was 0. I am sure the bombardment looked really impressive to everybody who was able to watch. The first ground assault would begin after naval infantry were landed and they would begin moving forward at roughly 5AM. One of the Polish defenders would later write that “I saw how the Germans advanced. They had white canvas rucksacks, two long-handle hand grenades each and egg grenades in a bag, also of white canvas. They made very good targets, with their dark uniforms and white canvas bags, very easy to see from a distance. But we didn’t have to strain our eyes, because we let them come as close as 30–40 meters [100 to 130 feet] before we opened fire.… Few of them came out alive.” The German marines really never had a chance in this early attack, the Polish resistance was far stronger than was anticipated and when they moved forward passed the outer depot wall they came under heavy fire from multiple different angles. The initial assault was a failure with pretty heavy German casualties, along with some Polish casualties. This would not be the last time that German troops would make the mistake of believing that they were just moving in to mop up whatever remained of Polish resistance only to be very quickly shown that the Polish defenses were largely unaffected by the pre-assault bombardment. After this first failure the German ground commander requested a much more powerful bombardment of the Polish positions. The Schlewig-Holstein would then fire 90 28cm and 47 15cm shells over the course of about 75 minutes before the second attack went forward just before 9AM. The result was largely the same, the Polish defenses were not destroyed by the bombardment and the defenders were more than ready to meet the German attack, resulting in another German retreat. Over the course of the two assaults the Germans would suffer 136 casualties, balanced against only 2 Polish defenders killed.

The second critical area of Danzig that would receive a large amount of German focus during the opening hours of the attack was the Danzig Post Office. The Post office building in Danzig had been granted to Polish as a fully sovereign piece of territory, this removed the limitations placed on other areas of Danzig around what the Polish could or could not place in Danzig, most importantly military preparations. During the summer of 1939 a few changes had been made and the men that were stationed in the Post Office were replaced by Polish reservists and members of the Polish militia. A Polish combat engineer was also dispatched to the Post office to work on covertly bolstering its defensive capabilities. The post office occupied the eastern wing of a four story L shaped building, which made it a solid defensive position to begin with. The major alteration made just before the start of the war was to brick up all of the interior passageways that linked the Post office in its wing to the Danzig Labour Office which occupied the rest of the building. The Germans who planned to assault the building were the 150 men under the command of the senior Danzig Police officer, with the unit made up primarily of Danzig police and the Danzig based Heimwehr SS. Much like during the opening attack at Westerplatte, here again the German attackers drastically underestimated the capabilities of the Polish defenders, and even though they were able to breach the brick walls that had been built inside the building they immediately came under concentrated small arms fire that prevented them from moving any further. There was also an attempt to attack into the building from the outside, an effort that was similarly repulsed. Undeterred from their ultimate purpose, the request was placed with the local SS Commander, Johannes Schaffer to send some assistance. Shafer’s men had spent the morning moving around Danzig taking control of buildings, train stations, and other areas largely without facing any resistance from the Poles. He now shifted his focus to providing assistance at the Post Office. And instead of launching more direct assaults, Schafer opted fore a more patient strategy. Artillery was brought in with two 7.5cm and one 10.5cm artillery pieces being available and placed to bring fire on the front entrance to the building. The 7.5cm guns would prove to be largely ineffective against the strong brick walls of the building, and at 5PM the Polish defenders were given the option of surrendering. When this was refused the second part of Shafers plan was put into action, because along with bringing in artillery Schafer had also ordered a pioneer unit to begin digging and tunneling toward the building’s foundation and at 5PM they detonated about 600kg of explosives near the front entrance which created a hole in the wall. As soon as the hole opened the 10.5cm gun began firing directly through the hole, followed by another assault, this finally forced the Polish defenders to retreat to the basement of the building. When it was clear that they still would not surrender, the decision was made to bring a fuel tanker up to the building and they began to pump gasoline into the basement, which was then ignited by a hand grenade. One of the Polish survivors of this inferno would later recall: “Everything went up in flames [and] we in the cellar were suffocating with the gases. We decided, because of the overwhelming German advantage, to give ourselves up. When we cried out that we surrender, the Germans ignored us and continued the attack” 11 of the defenders would be killed by the flames or by the burns they suffered, with the rest surrendering at 7PM. 44 defenders would surrender to the Germans, and just a month later almost all of them would be executed by firing squad after being tried under a military court as “irregulars”.

Along with the efforts of the Polish forces to defend the city of Danzig and its surroundings, in the nearby city of Gdynia the remainder of the Polish Navy Also began to put into action its war plans. There was not a lot of naval strength to work with, but what was still in Gdynia would do what it could. The minelayer Gryf attempted to fulfill its goal of laying mines near the Hel Peninsula, but as soon as it set sail it was attacked by German Stukas and the plan was aborted. The other major operation was for the five available submarines to begin offensive operations against any German ships near the Hel Peninsula, particularly aimed at preventing any kind of German amphibious landing. The submarines gave it a good try, but after the operation began on September 2 they would only be able to launch 3 torpedos with no successful connections. Due to the danger of being a submarine close to the coast on September 6, the submarines abandoned their positions and moved further north and into the deeper areas of the Baltic so that they would be less detectable and vulnerable. They would continue their patrol for the next several days, but after 11 days they began to run low on supplies. One Submarine would make its way to Britain, while four others would be interned in Sweden and Lithuania. The sum total of Polish naval operations during this period had a disappointing result, but they were so massively outnumbered that little more could really be expected.

Outside of their operations against Westerplatte and the Post Office, over the course of September 1st the Germans would fan out around the city and take full control, with 3,000 civilians arrested and sent to detention camps. Back at Westerplatte September 2nd would begin with the Polish defenders still holding off any German efforts to attack the depot. On the second day of the assault the Luftwaffe would take its turn at bombarding the Polish defenses, with over 50 Stukas being given the task, resulting in 26 tons of bombs being dropped on the area. This represented a very large concentration, because the area being bombed was quite small. Following this effort by the Luftwaffe, the German infantry would….wait a bit to attack. I’m not sure why they did this, but we do know that they did not immediately follow up the air attack with another ground effort. Instead, they would wait not hours, but several days before really taking another crack at Westerplatte, and it would not be until the early morning of September 7th that the final assault began. The days between September 2 and the 7th would be spent softening up the defenses through the use of 10.5cm and 21cm howitzers, before the Schleswig-Holstein was called in once again on the 7th. In the final assault at 5AM the effort put forth by the attackers was very different than the early attacks of September 1st, including the usage of flamethrowers to neutralize the Polish positions. The final surrender would occur at 11AM suffering 68 casualties, but inflicting 200 on the German attackers. Albert Forster, the Nazi party leader in Danzig would give a speech stating ‘The hour for which we have been longed for twenty years has come, as of today, Danzig has returned home to the Reich. We thank the Lord that he has given the Führer the strength and opportunity to free us from the evil of the Versailles Diktat.’

To the south of Danzig and Gdynia the final act of the defense of the city had already been completed when the units that had been based south of Danzig were forced to retreat. These forces were placed along the path between the city and the Army of Pomorze to the south which was positioned on the southern end of the corridor. Eventually German ground troops would arrive, and the Polish forces would have to surrender. As would frequently happen during the defense of Poland, this meant that some Polish soldiers who lived in the area were forced to leave their homes and their families behind, in areas that would inevitably be captured and occupied by the German invaders. Here is the account of Lieutenant Stodulski discussing this moment: “I kept my platoon for a while in the village of Cegielnia, in a small beech forest by the road, until the other platoon arrived. After a few minutes, the company’s commander, Lieutenant Perkowski and his platoon joined mine. The enemy was following right behind him and soon opened fire. I ran to the company commander and said, ‘Captain, let’s make a counter-attack’, but he responded that ‘there is no time to fight, the path of retreat is closing in front of us. Send two machine guns to the hill, which are to stop the enemy, the rest will retreat.’ As my platoon retreated, I said goodbye to my wife and three children, standing in front of Skrzypkowski’s hut. Great pain pierced my heart! I clenched my teeth so that I would not break into tears, squeezed my revolver and marched there with the platoon, where he ordered me.”

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We now shift our focus to the area south of East Prussia to the German attack that was planning to move south out of Prussia and towards Warsaw. This area was guarded by Army Modlin, which had two infantry divisions and two cavalry brigades. This force was not designed or assigned the task of stopping the German advance at the border. The assumption was that the Germans would muster enough forces to force Army Modlin to retreat, and when it did so the goal was for the Army to maintain as much of its strength as possible in a retreat to the Modlin fortress, which was located where the Narew and Vistula river came together north of Warsaw. The hope was that Army Modlin would be able to delay the German advance, providing additional time for the forces in and around Warsaw to mobilize and prepare to defend the city. Arranged against Army Modlin was the German Third Army, which planned to break through any resistance placed in front of them and then quickly advance all the way to the Vistula, with the hope being that the advance could be made in a single day, which would have meant an advance of 100km in just a day. They did know that there were some prepared Polish defenses that they would have to overcome, but they did not fully understand the extent of Polish preparations. One of the Polish infantry divisions had spent 6 weeks before the start of the war building defensive works, and they were aided by the geography of the area with a portion of the front being swampy enough to make armored operations very challenging. The most important area was around the village of Mlawa (muhwava) which was just 10 kilometers from the border. In this area there were earthworks, 49 concrete bunkers, barbed wire entanglements, anti-tank ditches, other anti-vehicle barriers. And that was just the first line of defenses, with another line further from the border that had more bunkers and defenses. With both lines of defenses combined they were able to cover 30 kilometers of territory, which the Germans would have to find a way either through or around if they wanted to continue on their way to Warsaw. Recognizing these two options, the two Polish cavalry brigades were placed one on each flank to help to prevent that possible end-around.

When the German troops crossed the border Army Modlin was quickly alerted and this allowed the troops to prepare themselves before the Germans arrived. The result was that when the men of the 11th Infantry Division and Panzer Division Kempf encountered the Polish positions they were stopped. Attempts were made to push forward and to capture certain villages, with the SS-Regiment Deutschland for example trying to take the village of Uniszki Zawadzkie, but they were unsuccessful. While the German infantry were attempting to push south towards Mlawa, Panzer Regiment 7 was waiting to exploit the expected break through, but when that breakthrough did not materialize the Panzer Regiment was also sent forward, but it quickly encountered problems. One piece of the Polish defenses was a 6 meter wide anti-tank ditch that the German tanks could not move through, and so the decision was made to drive along the ditch to try and find a way around the obstacle. This gave Polish anti-tank gunners the perfect opportunity to use their 37mm anti-tank guns against the German tanks, damaging 32 of them. Eventually the attack would have to be called off. Kempf, the commander and namesake of Panzer Division Kempf, would report to Third army headquarters that ‘The attack was a disaster. Terrible losses of Panzers, number unknown. An attack here is hopeless.’ With the challenges of attacking Mlawa directly, the decision was made for the primary focus of the German effort to be attacks to the East in an attempt to outflank the Polish defenses. On the first day of the attack the German 1st Infantry Division had attempted to make progress in this area, but to little success, and then on the second day the situation in the area would be much the same. The 11th and 61st Infantry divisions would attack on September 2nd to little gain, although the 12th would have slightly more success, forcing the Cavalry Brigade guarding the Polish right flank to withdraw 5 kilometers. As the German attacks developed on the Polish side they would also choose to withdraw the 79th infantry regiment to positions closer to Mlawa itself to prevent the line from being outflanked. Even though most of the attacks on the second day were unsuccessful, there was at least some progress and then would cause General Kuchler, Third army commander, to order Panzer-Division Kempf to reposition itself to the east to be ready for an attack on September third. The division would spend most of the night moving 45 kilometers each and it would not be until the middle of the afternoon that they were ready to actually begin their advance. However, once the attack rolled forward they were able to make some real progress for the first time, with several key villages to the east of Mlawa being in German hands by 4PM. This caused a kind of chain reaction along the Polish lines, as units were forced to retreat further south and west, jeopardizing the entire Polish front around Mlawa. Eventually the order had to be given for the defenses that had been held by the Polish 20th Infantry north of Mlawa to be abandoned out of fear that they would be surrounded. Brigadier General Anders of the Novogrodek Cavalry Brigade, which had previously been positioned to the West of Mlawa would recall: “When I finally reached the 20th Infantry Division, found it already in retreat. It had fought the enemy in excellent spirit and, when it could hold its positions no longer, had begun to retire in good order. But when I came up with it, the retreat had ceased to be orderly. Hundreds of German aircraft bombed the retiring columns, and even made attacks on soldiers moving in small groups across country.” Here is an account from Major Jozef Wojtaszewski “The bombing lasted about an hour and it was so intense that the sky was clouded with smoke and the bright autumn sun was no longer visible. When the squadrons flew away, the bombing was over, and the smoke dispersed, a blood-chilling sight appeared in front of us. Bodies were strewn across the road, and the horses that were killed were still in harness. The remnants of equipment and wagons were scattered about us. The trenches were full of slain soldiers; those that survived emerged but there were so few of them that in reality the 34th and 50th Infantry Regiments had ceased to exist.”

While the Polish retreat was being attacked from the air as it moved south, instead of focusing their efforts on surrounding and neutralizing the retreating Poles the orders would be sent straight from the top, General Bock commander of Army Group North, to focus on the capture of Rozan a town on the Narew river northeast of Warsaw, with the ultimate goal of pushing even further east to the city of Lomza near the Bug river. But before the Germans could reach such lofty objectives they first had to capture Roznan, and that would prove to be quite difficult. The town was defended by over 3,000 troops, largely Polish reservists, and a battalion of 75mm guns. Panzer-Division Kempf would be added to the German troops in the area and they would launch a three sided attack near mid-day, but with little success. The German infantry were unable to make much headway and the Germans would lose around 10 tanks to Polish anti-tank and artillery fire. There was an attempt to outflank the defenses once again, but in these efforts the Germans had to contend with the Narew river. Some units would be sent across the river in rubber boats, but they would be forced to retreat due to Polish resistance. Even though they were able to mount a defense on the afternoon of the September 5th, the Polish units were not in a position to hold Rozan indefinitely, and they were given the order to withdraw on the night of September 5th.

As the bulk of Army Modlin retreated south towards Fortress Modlin on the outskirts of Warsaw, and the Germans focused their efforts on moving East, there would be a lull in the fighting as the Polish forces entered and prepared to defend the fortress, which the Germans would not arrive at in force until September 10. The Battle of Mlawa would cost the Germans about 1,700 casualties, although as will always be the case there is a bit of a difference between various estimates and claims. On the Polish side casualties were around 2,700, with a large percentage of those occurring during the retreat from their forward positions as they made their way south and came under German air attack and German artillery fire. One of the primary reasons I placed this battle here in the first episode covering the ground operations is because it is a perfect example of what both armies were capable of. Given a prepared position the Polish defenders were very capable of holding their own against German attacks, and against the greater numbers of equipment that the Germans were able to bring to bear in any given engagement. But the German army was able to shift and move around the areas of greatest Polish strength which allowed them to best utilize units like armored and mechanized divisions to exploit the fact that the Polish troops simply could not cover every village or road with the same number of defenses. This is basically the template of the opening battles of the Polish campaign that we will see repeated time and time again, a group of Polish defenders will stop the Germans with their prepared defenses, but will then be outflanked by the German advance and forced to retreat. Next episode we will see this happen with Army Pomorze on the southern end of the Polish Corridor.