In 1939, the United Kingdom and France offered military support to Poland in the likely case of a German invasion. At dawn on 1 September 1939, the German invasion of Poland began. France and the United Kingdom declared war on 3 September, after an ultimatum for German forces immediately to withdraw their forces from Poland was not answered. Australia and New Zealand also declared war on 3 September, South Africa on 6 September and Canada on 10 September. While British and French commitments to Poland were met politically, the Allies failed to fulfill their military obligations to Poland. The possibility of Soviet assistance to Poland had ended with the Munich Agreement of 1938, after which the Soviet Union and Germany eventually negotiated the Nazi–Soviet Pact, which included an agreement to partition Poland. The Allies settled on a long-war strategy in which they would complete the rearmament plans of the 1930s while fighting a defensive land war against Germany and weakening its war economy with a trade blockade, ready for an eventual invasion of Germany.