As we highlighted in the previous section, the world was in diplomatic turbulence before the outbreak of the Second World War. However, the first military events which is understood to be the official beginning of the Second World War was the annexation of Poland by the Germans on 1st September 1939. The pretext that the Germans gave for invading Poland was that the Poles had launched a series of sabotage operations on the Polish/German border. This claim was eventually proved to be false.
The Germans invaded the country from the north and headed to the south and the west. One of the reasons that the invasion was so successful was because of the limited support from the British and the French, since the Poles expected much more support from them than they received in reality.
Just days after the invasion of Poland by Germany, the Soviets invaded Poland on 17th September. Poland was quick to fall to the Germans, this happened on the 27th September. The Germans were much stronger militarily and Poland had little realistic chance of being able to maintain their ground and eject Germany from their country. The occupation of Poland also saw the rise of resistance in Poland. This was an underground movement that used to work covertly to try and defeat the German occupation.
The Germans also exerted their power in Western Europe in the early stages of the war. Denmark and Norway were invaded in the April of 1940, just months after they had taken control of Poland in the east of the continent.
The events which preceded the Second World War were also critical here. Alliances were already being formed in many parts of the world, Japan was already ostracizing itself in the Far East and there were grave concerns about the actions of many European countries, primarily Germany, Spain, and Italy after they formed friendships during the Spanish Civil War.