Question: by September 1939 the writing was pretty much on the wall, that Germany invaded Poland should not have dropped monocles anywhere. Wasn't the German army fully mobilized? If so, why weren't the allied armies fully mobilized? WWI came to pass because once one empire mobilized, everyone one did, too, because everyone knew that time was critical.
Actually, the Allies were forcing Poland several times to delay mobilization to "not challenge Hitler"...
Ultimately, it was announced only on 30th August with the date of mobilization on 31st August. And yes, it was a major blow for Poland's ability to defend.