Where was the first Hitler invasion?
Hitler first invaded Austria. The Invasion of Poland was merely the invasion that was the catalyst for WWII; as that day September 1 1939, War was declared on Germany.
Hitler' s planned 1940 invasion of the British Isles with 160,000 troops was cancelled when the Luftwaffe failed to gain air superiority. Hitler then turned East and invaded the Soviet Union. Only an aerial attack was made on the UK during WWII. It could be said that the invasion of the Channel Islands was an invasion but no defense was made on their behalf because of their proximity to occupied France.
Hitlers first invasion was into Austria-HUngary, although this was done bloodlessly. His second invasion was into Poland, this is actually what triggered World War Two, as it directly broke the treaty of Versailles (despite Chamberlains policy of appeasement). Continuing on from that Hitler began to 'control' Italy and most of Europe, and parts of Africa were controlled by Hitler during the war, although slowly pushed back towards the end.
Hitler had some 60 divisions in France in case of an Allied invasion of Europe, but when Sicily was invaded by the Allies and Mussolini was captured, Hitler, not wanted the Allies in Continental Europe, invaded Northern Italy and Simultaneously sent a rescue team for Mussolini, there he established a puppet government for Mussolini