The Polish Military on the brink of WWII was on paper a relatively heavily armed nation in 1939: indeed, its military was probably on par numerically with the German military as late as 1937. It possessed sizable ground forces, significant fortifications along the German border (notably around Silesia and the area of Posen) as well as a sizable, relatively modern air force, and a modest brown-water navy. However, the Polish government was severely underprepared for war, and more importantly had misconducted its foreign policy.

Polish overall strategy considered the combined threat of both Germany and the Soviet Union. Both countries had desires upon Polish territory: the Germans, looking to reclaim at a minimum the Polish corridor and Silesia, and the Soviets, who looked to reclaim parts of Eastern Poland which had been conquered by the Poles in the Polish Soviet War of 1919. To counter this, Poland relied on a series of military alliances and guarantees, most especially with France and the United Kingdom, but also smaller countries such as Romania. The war plan against Germany made perfect sense if considered in isolation: Polish troops would hold their fortifications in the West against German attack while French and British troops would apply pressure to the Germans from the West. Reinforcement in Poland would arrive through Romanian ports on the Black Sea, thus stabilizing the Polish front against the German attack. This would allow the Poles to retain their strong front against the Soviet Union, and was politically attractive as well at the cost of being less conducive for military defense. Strong nationalist sentiment made a defense plan along the Vistula River, for instance, a political difficulty.

However, Poland made some foreign policy decisions which would end up hurting their overall cause. Most notably, Poland participated alongside Germany in the annexation of Czechoslovakia, which severely stung both France and the United Kingdom, and in context with the Polish refusal from the Polish Soviet War to listen to British and French advice, both Britain and France were wary of being dragged into war with Germany due to perceived Polish transgressions. This did not stop them from declaring war, but mobilization was sluggish in Britain and France and by the time an offensive was underway (the Saar Offensive) Polish resistance was already collapsing and the British and French instead retreated and awaited the German onslaught.

Similarly, Poland had conducted several foreign policy decisions in its east that hurt its ability to provide military help. Lithuania was still smarting after Polish-Lithuanian border disputes, most notably with the Polish seizure of Wilno/Vilnus. Ukraine had been abandoned by the Poles in the wake of the Polish-Soviet War and was now a Soviet Socialist Republic. Hungary and Romania were friendly to the Poles, but Hungary was a German ally and Romania's offer of military assistance was declined. Admittedly, Romania was also under severe German pressure to do nothing, as the radical Iron Guard Movement was very powerful and closely affiliated with the Nazis.

This created a situation whereby Poland was essentially deprived of any direct foreign aid in defense of her territories. However, this is only the first explanation as to why the Polish defenses collapsed so quickly.

Poland acquitted itself bravely against the German invasion in 1939, however their poor strategic position, insufficient mechanization, largely irrelevant air force, and especially the unexpected intrusion of the Soviet Union against their rear flank doomed their defensive plans. Nonetheless, while they were outmatched in many respects, they were largely aware of their deficiencies and consequently they had formulated a plan of battle which they hoped would play to their own strengths as much as possible. In general the Poles sought to fight from behind prepared defensive works in pitched, set-piece battles with the hope of holding out until their Western allies could come to their rescue. However, the war far outpaced the Polish ability to respond. Devastating air attacks in the early hours of the war rendered their air force irrelevant and allowed the Germans to prey upon troop concentrations and supply lines without contest. The war of maneuver which ensued was the worst possible outcome for the Polish because it made their problems of supply and communication even more difficult, such that many battles were lost due to an inability to coordinate defenses or counter-attacks, or the inability to muster the supplies necessary to carry their plans through. Even then the Army harbored hope in forming a South-eastern redoubt where the government and Polish nation could preserve itself until liberation. However, the sudden intervention of the Soviet Army on the Eastern border rendered this plan impossible, and the only hope left was to save whatever could be saved in order to carry on from England.

The primary difficulty facing Poland was the fact that there was very little defensible terrain between the German border and Warsaw. Major Kennedy of the United States Army’s blunt assessment was that “the country possesses no good natural defensive lines, except to a limited degree in the Carpathian mountains in the south.” Although Poland had planned and begun defensive lines along the Vistula, Narew and San rivers, the protrusion of Eastern Prussia to its North greatly complicated their ability to defend those lines, because whatever forces the Poles committed, even if sufficient to stop the German advance across the river, would simply be outflanked.

Poland’s industrial base was also somewhat limited despite the intense effort of the preceding years. Consequently, once war began the Polish Army was largely reliant upon whatever supplies they had managed to stockpile, because they could not expect sustained replenishment. This problem was further exacerbated by Polish reliance on trains alone as a means of mechanized transport, because “the relatively immobile stocks of ammunition, fuel, and other critical supplies would be vulnerable to capture in war.”

On paper, Poland had a nominal strength of more than 1,750,000 men that could bear arms if called upon, but the vast majority of them would be reservists without the training and experience of those that they would oppose. Even so, fighting from prepared positions, they were expected to acquit themselves fairly well. And, when given the opportunity at Danzig and Warsaw, they did. However, the results of the campaign show that the Germans were adept at outmaneuvering stubborn opposition whenever it was perceived in time. Furthermore, though the Wehrmacht was hardly the mechanized behemoth that the American Army would grow into, the Polish Army was even more reliant upon horse-drawn conveyance, which severely limited its strategic mobility.

As for the more modern tools of war; tanks, artillery, anti-tank guns and planes, the Poles were not wholly bereft, but they simply could not match up against their opposition. For artillery they boasted many of the quick-firing French 75’s which had been kings of the last war, and were still very relevant, but “the artillery regiment [often] lacked one or more of its battalions or the battalion one battery.” They were also rarely equipped to move their pieces should they be called to do so. All artillery-oriented units, whether bombardment, anti-tank or anti-air, also suffered from a lack of supplies, and in a number of battles they were put out of action not by enemy initiative, but by lack of ammunition. As for the air, the Polish Army boasted 935 aircraft in 1939, but of those “a large number were… obsolete or obsolescent, and suitable only for training purposes.” The Poles maintained no tank force worth mentioning.

Additionally, their war plans, while correctly anticipating the general thrust of the coming German invasion, were overambitious because they represented an attempt to defend the entire country. While it may have been felt to be politically necessary to attempt a defense of all Polish soil, Major Kennedy describes their disposition as “faulty from a military standpoint,” and he argues that it was a plan which was based upon “the belief that the intervention of Britain and France in the west would force a number of German divisions to withdraw.” As history proved, neither France nor Britain was prepared to make any such intervention.

When war broke out on September 1st it opened with a major defeat for the Polish because the Germans had achieved tactical surprise and destroyed almost the entire Polish air force on the ground. The following German superiority in the air set the stage for a campaign which was ruled by the German ability to interdict Polish plans before they came to fruition. The second major defeat for the Poles came when the area south of Gdánsk and about Poznán was cut off in the first of what would be many encirclements of Polish concentrations. Of these, the most notable were the entrapments of many units west of the Vistula and in the vicinity of Krakow, because it was so indicative of Polish inability to maneuver effectively. At fault was not only their lack of mechanization, but also the effective deployment of Panzer spearheads and air-interdiction by the Germans.

This isn’t, however, to say that the Poles were entirely inept, or that their situation was hopeless. Even though they were encircled, the soldiers near Poznán still represented a significant force, the men in the fortress of Gdánsk were holding heroically, mountain troops along the southern border had significantly delayed German advances, and the lines before Warsaw, albeit bending, were not yet broken. However, a series of unsuccessful counter-attacks against the German Tenth Army and near Radom only worsened their position. The involved units were again hampered by communication and supply issues. When France and England’s declarations of war did not bring the hoped for relief, “it was only a question of time until the German Army would overrun Poland.”

Even so, some Poles held out hope for the establishment of final defensive lines in the more mountainous areas near Romania, however the invasion of the Russians on September 16th spelled doom to these plans. During those two days morale in the Polish army collapsed, and prisoners taken during that time “represented half the identified Polish divisions and almost one-third of the cavalry brigades, and their statements indicated complete despair on the part of the remnants of the Polish Army.”

In conclusion, the Polish Army was not necessarily backwards or primitive – the infamous cavalry brigades were actually trained to fight as dragoons and were well equipped with anti-tank weapons. Instead, they were simply under-equipped and under-supplied, and ill-prepared to fight a war of maneuver. What’s more, nearly every circumstance conspired against them. From the sudden and nearly complete destruction of their airforce to the lack of expected aid from the Allies up unto the betrayal by the Soviet Union, Poland during World War 2 was simply sore beset from every side. For everything that they did right, and they had done as much as might be reasonably expected by mobilizing their reserves, beginning work on defensive works and rushing to better equip their armed forces all in the face of correctly anticipated German assault, their poor strategic position was a disadvantage that they could not alter and could not overcome.

All quoted selections are taken from Major Robert M. Kennedy's (no, not that one) 1956 report on "The German Campaign In Poland" This is necessarily a limited view, as it is what I have most readily available as a reference. For more detailed information, other scholarship like Stephen Zaloga and Victor Madej's "September Campaign," and "Poland 1939: The Birth of Blitzkrieg" by Zaloga should be considered.