Invasion of Poland

• 1. Introduction

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  At 04:45 on the 1st of September 1939, the old German battleship Schleswig-Holstein opened fire on a Polish military depot at Westerplatte, in the Free City of Danzig. Within hours, bombers were striking cities. By morning, three separate invasion forces were driving into Poland from the north, south, and west. The world had entered a new kind of war.

  The invasion of Poland, also known as the September Campaign, was not just the opening act of World War II. It was a joint assault by Nazi Germany, the Slovak Republic, and the Soviet Union against a country whose allies had promised to defend it. It lasted thirty-five days. It ended a sovereign republic that had existed for barely two decades. And it set in motion a cascade of violence that would consume tens of millions of lives.

  What made this campaign possible? How did Poland plan to defend itself, and why did those plans collapse so quickly? What role did the Soviet Union play, and what happened after the guns fell silent? The answers involve secret protocols, staged provocations, a drug distributed to keep soldiers awake, a cavalry charge that never happened, and a gold reserve quietly shipped to London and Ottawa before it could be seized.

• 2. The Road to War

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  On the 30th of January 1933, Adolf Hitler came to power in Germany, and his foreign policy toward Poland began not with hostility but with a calculated friendliness. The German-Polish Non-Aggression Pact of 1934 was part of a deliberate effort to weaken ties between Poland and France, and to manoeuvre Poland into an anti-Soviet alliance. Poland would be offered territory in Ukraine and Belarus in exchange for becoming, in effect, a German client state.

  The Poles refused. They understood the offer's terms clearly. Hitler had written in 1930 that Poles and Czechs were a "rabble not worth a penny more than the inhabitants of Sudan or India," and had denied their right to independence. Polish leaders distrusted him and feared that accepting German demands would lead to the loss of sovereignty altogether.

  By 1937, Germany's demands shifted to the city of Danzig and the Polish Corridor, the strip of land that separated East Prussia from the rest of Germany. Danzig had a German majority and had been made a nominally independent free city after the Treaty of Versailles. Hitler wanted it back, along with an extraterritorial roadway through the Corridor. When Poland rejected these demands, Hitler used them as a pretext rather than a genuine grievance. He told his generals privately in May 1939 that Danzig was not the real objective. The goal was Lebensraum, living space in the east.

  On the 28th of April 1939, Hitler unilaterally withdrew from both the German-Polish Non-Aggression Pact and the Anglo-German Naval Agreement of 1935. Diplomatic talks collapsed entirely. Then came the critical diplomatic coup: on the 24th of August 1939, Germany and the Soviet Union signed the Molotov-Ribbentrop Pact. A secret protocol divided Eastern Europe into two spheres of influence, with the western third of Poland going to Germany and the eastern two-thirds to the Soviet Union. The possibility of Soviet opposition to a German campaign in Poland was neutralized overnight.

• 3. Two Armies, One Border

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  Germany's military advantages over Poland in 1939 were substantial in almost every dimension. The German army fielded seven Panzer divisions with a combined total of 2,009 tanks, operating under a doctrine designed to punch through enemy lines, isolate units, and destroy them before slower forces caught up. The Luftwaffe brought close to 4,000 aircraft into the campaign, including 290 Ju 87 Stuka dive bombers and 1,100 conventional bombers. Having participated in the Spanish Civil War, the Luftwaffe was arguably the most experienced, best-trained, and best-equipped air force in the world at that moment.

  Poland's situation was more complicated than outright weakness. The Second Polish Republic had emerged as an independent country only in 1918, after 123 years of partition during which the occupying powers had deliberately withheld investment in Polish industry. Between 1936 and 1939, Poland invested heavily in a newly created Central Industrial Region, and in 1936 established a National Defence Fund to build up its armed forces. But most defence plans assumed that any serious conflict would not begin before 1942.

  The Polish Air Force was not destroyed on the ground, as German propaganda later claimed. Its aircraft had been dispersed to small camouflaged airfields before the fighting began, and not a single combat plane was lost on the ground in the first days of the war. The pilots were among the best trained in the world, a fact they would demonstrate a year later in the Battle of Britain. But their aircraft were old. The PZL P.11 fighter had been built in the early 1930s and reached a top speed of only 365 km/h, which was slower than many German bombers. A last-minute order for 160 French Morane-Saulnier M.S.406 fighters and 111 British aircraft had been placed in the summer of 1939, with the first shipment leaving Liverpool on the 28th of August, but none of those planes arrived in time to fly a single combat mission.

  Poland's standard tank, the 7TP light tank, was actually ahead of its German equivalents in certain respects. It was the first tank in the world fitted with a diesel engine and a 360-degree Gundlach periscope, and it outgunned the German Panzer I and II. But only 140 had been produced between 1935 and the outbreak of war.

• 4. The Plan and Its Collapse

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  The German September Campaign was devised by General Franz Halder and directed by General Walther von Brauchitsch. Fall Weiss, as the plan was called, aimed to converge three invasion forces on Warsaw while encircling and destroying the main Polish army west of the Vistula River. Hitler demanded Poland be conquered in six weeks; German planners privately believed it would take three months.

  Poland's defence plan, known as Plan West, was shaped partly by political pressure. Poland's most valuable industry and resources lay in the western regions near the German border. Polish politicians feared that pulling forces back behind the Vistula and San Rivers would allow Germany to occupy the disputed territories and then negotiate a separate peace with Britain and France, as had happened at Munich in 1938. So Polish forces were stretched thinly along the border rather than concentrated behind natural barriers, as French advisers had recommended.

  The consequences were swift. By the 3rd of September, German armoured forces under Walther von Reichenau had crossed the Warta River, and his left wing was already well to the rear of Lodz. By the 8th of September, one of his armoured corps had advanced 225 km in the first week and reached the outskirts of Warsaw. By the 12th of September, all of Poland west of the Vistula had been conquered except for the isolated capital.

  The largest single battle of the campaign, the Battle of Bzura, unfolded from the 9th to the 19th of September near the Bzura River west of Warsaw. The Polish armies Poznan and Pomorze attacked the flank of the advancing German 8th Army and achieved initial success. But the Luftwaffe intervened with devastating force, destroying bridges across the Bzura and trapping Polish forces in the open. Wave after wave of Stukas dropped 50 kg bombs, and when Polish anti-aircraft batteries ran out of ammunition and retreated to the forests, Heinkel He 111s and Dornier Do 17s dropped 100 kg incendiaries to smoke them out. The Stuka wings alone dropped 388 tonnes of bombs during that battle.

• 5. The Soviet Blow

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  Soviet forces had been waiting. The Red Army held at its designated invasion points while a separate conflict was resolved: a five-month undeclared war with Japan in the Far East. On the 15th of September 1939, the Soviet Union and Japan agreed on a ceasefire. One day later, the Nomonhan armistice went into effect. On the 17th of September, with no threat from the east, Soviet Premier Joseph Stalin ordered over 800,000 Red Army soldiers into eastern Poland.

  The justification offered by Soviet diplomacy was fabricated. Officials claimed they were protecting Ukrainian and Belarusian minorities since the Polish government had abandoned the country and the Polish state had ceased to exist. In private, Stalin was explicit about his reasoning. On the 7th of September, he explained to a colleague that the war between Germany and the Western powers was to the Soviet Union's advantage. He said that if Poland were destroyed, that would mean one fewer bourgeois fascist state to contend with, and the Soviet system could be extended onto new territories.

  The Polish government had oriented its entire remaining defence strategy around holding the Romanian Bridgehead in the southeast, waiting for Britain and France to strike Germany from the west. The Soviet invasion from the east made that plan immediately obsolete. Polish border defence forces in the east, the Korpus Ochrony Pogranicza, were ordered to fall back and avoid engaging the Soviets. Nevertheless, some clashes occurred, including the Battle of Grodno. Soviet forces executed Polish officers, including prisoners of war such as General Jozef Olszyna-Wilczynski.

  Lwow, a major city in eastern Poland, had been under German siege for more than a week when, in mid-siege, German troops handed operations over to their Soviet allies. The city capitulated on the 22nd of September. That same day, at Brest-Litovsk, a different kind of scene unfolded: the German 19th Panzer Corps under General Heinz Guderian had occupied a city that lay within the Soviet sphere of interest. When the Soviet 29th Tank Brigade under Semyon Krivoshein approached, both commanders agreed the Germans would withdraw with a ceremonial salute. Soviet and German officers held a joint victory parade before the German forces withdrew westward.

• 6. Civilian Catastrophe

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  From the first hours of the invasion, the Luftwaffe attacked not just military targets but columns of civilians on the roads. The bombing of Warsaw killed between 6,000 and 7,000 civilians. Altogether, civilian losses of the Polish population during the campaign amounted to roughly 100,000, or by other estimates between 150,000 and 200,000, the large majority caused by German military operations and terror. In Warsaw alone, between 15,000 and 25,000 civilians died.

  The campaign marked the opening phase of what would later be called the Holocaust. Operation Tannenberg, carried out by the Wehrmacht and the Einsatzgruppen in German-occupied territories, was a mass ethnic cleansing campaign begun during the hostilities themselves. Among those killed in the Intelligenzaktion operations of 1939-1940, approximately 61,000 were members of the Polish intelligentsia: scholars, clergy, and former officers identified as political targets in a Special Prosecution Book compiled before the war even began.

  German forces also used a recently developed methamphetamine called Pervitin during the campaign. It enabled troops to stay awake and in constant motion for several days at a stretch. The same drug was later distributed officially during the invasions of France and the Soviet Union.

  The German occupation that followed the campaign ultimately resulted in between 5.47 million and 5.67 million Polish deaths, roughly one-sixth of the country's total population and over 90% of its Jewish minority. That figure included the mass murder of 3 million Polish citizens, mainly Jews, in extermination camps like Auschwitz and in numerous ad hoc massacres. The approximately 75 tonnes of Polish national gold that had been quietly evacuated through Romania to London and Ottawa before the invasion fell was considered sufficient to fund a fighting force for the duration of the war.

• 7. Myths and the Record

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  One of the most persistent images associated with the September Campaign is that of Polish cavalry charging German tanks with lances and swords. It did not happen. At the Battle of Tuchola Forest on the 1st of September 1939, the 18th Pomeranian Uhlan Regiment was covering a Polish infantry retreat when it encountered elements of Heinz Guderian's 20th Infantry Division. Commander Kazimierz Mastalerz ordered an attack that succeeded: the German infantry was forced to withdraw and disperse. During redeployment, however, the Uhlans came under fire from German armoured reconnaissance vehicles and suffered heavy casualties.

  A group of German and Italian war correspondents who visited the battlefield saw the dead cavalry horses among the armoured cars. Italian journalist Indro Montanelli published a story in the Corriere della Sera about brave Polish cavalrymen charging German tanks with sabres and lances. Historian Steven Zaloga wrote in his 2004 book Poland 1939: The Birth of Blitzkrieg that this image dominated popular perception of the campaign despite being a myth created by German wartime propaganda and, as he noted, sometimes embraced by the Poles themselves as a symbol of wartime gallantry. In 1939, cavalry units made up 10% of the Polish army, and they functioned as mobile mounted infantry rather than as a relic formation.

  Poland also inflicted more damage on Germany than the speed of its defeat might suggest. The September Campaign cost the Germans roughly 45,000 casualties and the loss or destruction of 993 tanks and armoured cars, 565 to 697 airplanes, and 370 artillery pieces. The campaign lasted about a week and a half less than the Battle of France in 1940, even though the Anglo-French forces in France were far closer to parity with Germany and were backed by the Maginot line. The last operational Polish unit, General Franciszek Kleeberg's Samodzielna Grupa Operacyjna Polesie, surrendered after the four-day Battle of Kock near Lublin on the 6th of October, but Poland never issued a formal surrender.