World War II begins -- from Bonhoeffer: Pastor, Martyr, Prophet, Spy by Eric Metaxas:
Back in March , when Hitler had marched on Prague, Neville Chamberlain set down his teacup and took notice. It was then, exchanging one of his carrots for a stick, he vowed that Britain would defend Poland if Hitler attacked it. That time had come. But Hitler couldn't simply attack. He must first make it look like self-defense. So on August 22, he told his generals, "I shall give a propagandist reason for starting the war; never mind whether it is plausible or not. The victor will not be asked afterward whether he told the truth."
The plan was for the SS, dressed in Polish uniforms, to attack a German radio station on the Polish border. To make the whole thing authentic, they would need German "casualties." They decided to use concentration camp inmates, whom they vilely referred to as Konserve (canned goods). These victims of Germany would be dressed as German soldiers. In the end only one man was murdered for this purpose, via lethal injection, and afterward shot several times to give the appearance that he had been killed by Polish soldiers. The deliberate murder of a human being for the purposes of deceiving the world seems a perfectly fitting inaugural act for what was to follow. This took place on schedule, August 31.
In "retaliation," German troops marched into Poland at dawn on September 1. Göring's Luftwaffe rained hell from the skies, deliberately killing civilians. Civilians were murdered more carefully on the ground. It was a coldly deliberate act of terror by intentional mass murder, never before seen in modern times, and it was the Poles' first bitter taste of the Nazi ruthlessness they would come to know so well. The outside world would not hear details for some time. It knew only that German forces were cutting through Poland like the proverbial hot knife through butter as Panzer divisions neatly erased thirty and forty miles of Poland per day.
But Hitler gave a speech to the Reichstag, casting himself in the role of aggrieved victim. "You know the endless attempts I made for a peaceful clarification and understanding of the problems of Austria," he said, "and later of the problem of the Sudetenland, Bohemia and Moravia. It was all in vain." Poland had refused his gracious offers of peace and with a callousness not to be borne. The Poles rewarded his good faith with violence! "I am wrongly judged if my love of peace and patience are mistaken for weakness or even cowardice. . . . I have therefore resolved to speak to Poland in the same language that Poland for months past has used toward us." The long-suffering and peace-loving Führer could take it no more: "This night for the first time Polish regular soldiers fired on our own territory. Since 5:45 A.M. we have been returning the fire, and from now on bombs will be met with bombs." Admiral Canaris, the head of the Abwehr, had long dreaded this hour. He was overcome with emotion at the implications of it all. Hans Bernd Gisevius, a diplomat whom Canaris had recruited to work with him in the Resistance, was at OKW headquarters that day. They ran into each other in a back stairway, and Canaris drew Gisevius aside. "This means the end of Germany," he said. (pp. 347-8)
Two days later Britain and France declared war on Germany. Canaris would later be executed (alongside Dietrich Bonhoeffer) for his leadership of the plots against Hitler.
BTW this excellent biography is just out in paperback.