On this day, World War II began with the German invasion of Poland. The Luftwaffe (German Air Force) bombed Poland's airfields, and the navy attacked the ships. Hitler went as far as to declare that this was a defensive attack, which he supported by releasing propaganda to convince the world stage that this was the truth. As Britain signed an agreement with Poland to come to their aid, they declared war on Germany two days later, which officiated World War II. Australia, New Zealand, India, and France followed Britain. The Germans’ occupied Poland within four weeks with the help of the USSR. Finally, on September 28, the Germans split the land between Germany and the USSR, and all the Polish officials fled. The Nazi invasion of Poland started the ghettoization of the Jewish community, and the building of concentration camps began. Before WWII, there were about 3.5 million Jews in Poland, but by the war's end, only 350,000 remained. The Nazis built major extermination camps throughout Poland, in Auschwitz, Chelmno, Majdanek, and Treblinka. Jews on the German side of Poland perished in extermination camps. When Germany invaded the USSR half of Poland, they killed many Jews by conducting mass shootings in the forests. Poland stayed under German control until 1945.