6th September 1939
Poland : German troops captured the Upper Silesian industrial area in Poland. In the fields outside the Polish village of Mrocza, the Germans shot nineteen Polish officers who had already surrendered, after fighting tenaciously against a German tank unit. Other Polish prisoners-of-war were locked into a railwayman’s hut which was then set on fire. They were burned to death. Henceforth, prisoners-of-war were not to know if the accepted rules of war, as laid down by successive Geneva Conventions, were to apply to them: the rules whereby the Nazis acted were completely at variance with those which had evolved over the previous century.
South Africa : South Africa declared war on Germany after tough Cabinet battle.
UK : German aircraft attacked Great Britain for the first time. Four German JU-88 bombers were shot down by RAF Hurricane fighters and anti aircraft gunners over Rosyth. The first Royal Air Force fighter pilot to be killed during the war lost his life when two Hurricane fighters were shot down in error by two Spitfire fighters.
South Atlantic : German submarine shelled and sank British cargo ship Manaar off Portugal. Another German submarine U-47 torpedoed , shelled and sank British cargo ship Rio Claro off Cape Finistere , Spain
7 September 1939
Germany : French Army (5th and 6th Armies) entered the Saarland region of Germany, but made no move on the Westwall and after capturing two villages on the border temporarily , retreated back to French frontier.
Poland : German troops captured Kraków, Poland. In western Poland, the German 30th Infantry Division crossed the Warta River (German: Warthe) on bridges erected by German engineers.
The city of Łódź, Poland was captured by the German 8th Army after the Polish Łódź Army failed to halt their advance. In the Poznan sector, nineteen Polish divisions—virtually the same number of troops which Britain wished to have ready for action in March 1940—were surrounded; in the ensuing battle on the River Bzura, 170,000 Polish soldiers were taken prisoner.
UK : The BBC began broadcasts in Polish.
Atlantic Ocean : September 7 saw the inauguration of the first two convoys of merchant ships, escorted by destroyers, one from the Thames estuary, through the English Channel and into the Atlantic, one from Liverpool into the Atlantic. Meanwhile in Soth Atlantic , British cargo vessel Gartavon was sheled and sunk by German submarine U-47 off Spain. Another British cargo vessel Olivegrove was also torpedoed and sunk by U-33 off Spain. British cargo ship Pukkastan was torpedoed , sheled and sunk by U-34 off Land’s End Cornwall.
German coaster Lianne struck a mine and sunk off Norway. German cargo ship Vegesack ran aground off Tananger off Norway and declared a total loss.