Translated excerpt from the preface to Part II ("Operations between 1 and 8 September") of Volume I ("September campaign 1939") of "Polish Armed Forces in WW2" study, written by the Historical Commission of the Polish General Staff in London, published by the General Sikorski Historical Institute in London (2nd edition, 1986):
"(...) September campaign was most certainly the largest military defeat in our past. During its stormy course individuals often failed and there were also instances of collective breakdowns. There is of course no shortage of episodes painfully harming our national ambition and soldier's pride. History of this campaign must be thus out of necessity an unpleasant, or even painful reading for any Pole. Especially for readers not very acquainted with the history of warfare this reading will be very hard. For this reason at the beginning we want to direct reader's attention to some indispensible things, when it comes to fair evaluation of that sad reality. Namely, that it is a well-established fact that in initial campaigns, in wars fought after long periods of peacetime - and this applies to the September campaign - always many things go incoherently (clumsily) and unskilfully (inefficiently), a large percentage of commanders and units disappoint and generally such kinds of mistakes are commited, which would be simply unthinkable in later stages of the war. The reason of this is undoubtedly the fact, that versatile (broad) and complete preparation of armed forces to war is a very hard thing to achieve during peacetime, or even - as it seems - in some aspects unattainable. For it is impossible in peacetime conditions to provide the armed forces with complete picture of wartime reality and for this reason, in initial campaigns, this reality is always a greater or lesser surprise for a soldier. This refers to both of the opposing sides, but especially vulnerable in this respect (in respect of surprise) is always the weaker side, which after loosing initiative of operations is doomed for defence and for retreat. This was always the case, even if subsequent wars did not differ much from each other. Let alone in the September campaign, which after all had a totally new nature. Everything indicates, that this campaign demarcates between two large epochs in the history of warfare, because during this campaign for the first time, thanks to usage of Schnelle Truppen and Air Force on a vast scale by Germans, an agelong ratio of time to space (1 day and night = at most 25 km), intransgressible until that time when it comes to huge masses of troops, ceased to be in effect. It was a real revolution on the battlefield and in entire theatre of war, and one of its results was the increase in dread of war. This new reality was of course for commanders and soldiers on the Polish side a surprise in a way collateral. (...) It must be said that in military historiography (also in staff studies) there exists a kind of constant tendency to treat defeats and failures as shameful and embarrassing corners. They are being described in the most parsimonious possible way, they are often being sugarcoated, and sometimes - especially if during the course of further combats the tide turned - many things are totally omitted. Already Clausewitz considered this as unreasonable and very harmful. "We must truly ascertain the insane foolishness, when we see, that nearly all armies apply the principle of acknowledging (announcing) as little information (news) about unfortunate war events as possible." In our case this question is solved by the instruction of the Chef of General Staff, who ordered the historical commission to write a study that should be "a document of impartial historical truth". (...) Only in the light of diligently established facts a fair evaluation of the role of the September campaign in totality of WW2 will be possible. From this fact arises the need for as much objectivity as possible, and exclusive Polish point of view can only be marked in striving for not overlooking (not ignoring) brighter aspects of the campaign and for not showing anything in darker light than irrefutably emerges from analysis of sources."
There are words which carry the presage of defeat. Defence is such a word. What is the result of an even victorious defence? The next attempt of imposing it to that weaker, defender. The attacker, despite temporary setback, feels the master of situation.