On 1 Sep 1939, Germany invaded Poland from the north, west and south. The Germans invaded with 1.5 million soldiers against Poland’s 300,000, though Poland had 1.6 million still mobilizing in its reserves. This three pronged attack made Greater and Lesser Poland untenable, so Poles did what they’ve done for a millennium: delay until they could make a stand along one of the various river lines that bisected the country. Or failing that form a redoubt in the Carpathian Mountains along the Romanian border. They chose the Warta River first but because the French insisted that Poland not mobilize before hostilities commence, in order to “not provoke” the Germans, the Germans broke through that on 6 Sep.
The battle for Poland was a bit more evenly matched than the German propagandists, and the historians that took them at face value, suggest. The German Army that invaded Poland was 1.5 million strong but of the 60 or so German divisions that participated, only five were Panzer, and five more motorized. The vast majority were still foot and horse bound. Additionally, the German tanks of the panzer divisions were mostly obsolete, even by 1939 standards. Of the 2500, most were PzI or PzIIs, little better than machine gun carriers. Only about 1000 were the better Czech Pz35 or Pz38s, or the PzIII or PzIVs. The Poles had 800 tanks: about half obsolete Polish Tankettes, Brit Mk6s, and French Ft-17s, but the other half were the Polish 7TPs or French R35s which were equivalent of the German armor. The difference was in how these resources were used, though not as how you might have learned.
The Germans used a form of JFC Fuller’s Breakthrough theory called Blitzkrieg or Lightning War but in Poland it hadn’t come to fruition yet. The short version of Blitzkrieg is the armor punches a hole and surrounds the enemy while supported by airpower, and the infantry and artillery reduce the pocket. This is precisely what did NOT happen in Poland. JFC Fuller envisioned massive armored columns smashing through lines and continuing on. Even a casual perusal of the various panzer commanders’ memoirs, particularly Guderian, Von Luck and Manstein, show that in Poland the panzers smashed through the lines… then ran out of fuel or broke down. The vehicles were not reliable enough and supply systems could not keep up. These highly touted panzer breakthroughs devolved into immobile columns subject to the very effective French 37mm anti-tank gun or French artillery, which the Poles had oodles of, or being cut off and surrounded by counterattacks of mobile Polish cavalry brigades (whom rode to battle on horses but fought on foot… just like the German cavalry). The panzer divisions, almost universally, had to wait for the German infantry to break through to them so they could get some fuel and spare parts, and then continue on. (It’s a credit to the Wehrmacht that they figured this problem out by the campaign in France the next year).
Though the panzer portion of Blitzkrieg was a complete failure, the infantry were having much more success. Blitzkrieg’s mission style orders and the Wehrmacht’s reliance on machine guns and mortars at the very lowest level meant that German squads and platoons were consistently outfighting Polish companies and battalions. Furthermore, if there was a particularly tenacious strongpoint, they had the help of the Luftwaffe or German air force which had control of the air.
The Luftwaffe had 2500 planes to about 700 Polish planes. In the beginning, the Poles knew this but made the mistake of saving their strength for a massive aerial counterattack. Unfortunately, the Luftwaffe wiped out the Polish air force’s command and control in the first days of the war, so for the next month Poland’s air force was destroyed in uncoordinated penny packet counterattacks. Although the Poles shot down 40% of all German planes in theatre, they couldn’t prevent the real war winner for the Germans: Luftwaffe close air support of the infantry divisions.
As the infantry fought toward the cut off panzer divisions, the Luftwaffe shifted its supporting attacks from the immobile panzers, to the much more successful foot bound infantry, if only to save the panzers more quickly from Polish anti-tank guns. This went on for about a week in Sep 1939, until the Poles were fully mobilized to a strength of 2 million and prepared to defend the hills and forests of Masovia along the Vistula River, particularly the traditional fortress city of Warsaw. There they would hold out and wait for France and Great Britain’s promised attack from the west.
The Brits and French attacked and failed.
The French were big fans of Fuller also, and after the defensive fortifications of the Maginot Line were built, they built tanks with a vengeance. The nice thing about starting production late was you produced the latest models. The H35, Char B1 bis, the S35, the R35, AMR 35, Char D1 and D2, were all either equivalent or superior to the PzIIIs or PzIVs, and the French had more, many more. To great fanfare and in the largest and most literal expression of JFC Fuller’s Breakthrough Theory, the French launched their Armored Leviathan at the Germans on 8 Sep 1939… and promptly ran into large fields of inexpensive German mines. The French tankers were stuck. At least the Germans had infantry traveling with the panzers in trucks, the French didn’t even have that. They were completely flummoxed by the mines and had no way forward. So they went home.
The British launched their own offensive against the Germans, but they used bombers. The Brits were big fans of the Italian airpower theorist Giulio Douhet. Douhet’s theory is basically Fuller’s theory applied to bombers and he believed “that the bombers will always get through”. Douhet envisioned heavy bombers protected by on-board machine guns that would rain death upon the enemy’s cities. This would continue until the population’s will was broken and they sued for peace. To Douhet, land power was obsolete. The British Bomber Command launched its bombers against Germany the day after Britain declared war… and were promptly shot down by German anti-aircraft guns. The German 88mm, which was designed with Douhet in mind, was especially deadly. When the British tried flying lower to avoid them, they were shot down by the magnificently made Swedish Bofors 40mm or Swiss Oerklion 20mm anti-aircraft guns. The British Bomber Command took so many losses in the first weeks of the war that if it continued they wouldn’t have any bombers by November, so they switched to ineffectual nighttime bombing. The Poles were on their own for a while.
But this wasn’t war ending because by 9 Sep, the Poles outnumbered the Germans and were holding their own along the Vistula and in the Carpathians. They even launched a large counterattack at Bzura and repulsed the initial German attacks on Warsaw. Unfortunately on 9 Sep the German propaganda minister Josef Goebbels announced to the world that the Germans had reached Warsaw. The German people thought they had won and were jubilant. Goebbels ran with it. Poland had no way of contradicting Goebbel’s message. The British, French, and Soviets all soon believed Poland was lost. This absolved the Brits and French from any further assistance, and on 11 Sep, 1939 Stalin decided he’d better invade Poland before the Germans took it all.
On 19 Sep 1939, ten days after the Poles were supposedly defeated by the Germans, Soviet forces crossed the Polish frontier from the east, and made defense along the Vistula pointless. On 25 Sep, the Polish government announced the evacuation of the country. The last Polish army unit only surrendered on 6 Oct – a month after the war had supposedly been lost.
Fuller and his disciples: the Germans and French with their tanks, were defeated by unarmored fuel trucks, exposed supply lines, and inexpensive mines; Douhet and his disciples: the British with their bombers, were defeated by simple anti-aircraft guns; and Poland was defeated by bad diplomacy, information operations, mission command, and close air support.