Hitler used a tactic called blitzkrieg which is basically where you kill everything in your way also he VERY heavy tanks the best firepower of all the tanks used by other countries in WWII also he began using areal combat and would attack from the most unexpected place possible he also invaded France with paratroopers which France was major if he planned to win the war and most of all he made a agreement with Russia to not attack each other so he wasn't being attacked on their eastern border and also hitler made the Germans a country with the only politician group in power the nazi party
The Germans invented modern mechanized warfare where most of the countries were not equally equipped, as compared to the Germans. During invasion of the countries, Hitler widely used tanks which other countries could not stand.
Hitler had a lot of charisma, so his troops wanted to fight for him. His backing from Mussolini gave him a large force. Since Germany annexed Prussia at the end of World War One, Germany had very advanced weapons technology, combine that with the good strategic location of Germany on the map, and conquering Europe from that vantage point would be easy for almost anyone.
He had a big and powerful military, axis tanks and planes were properly armored. Axis troops came in big numbers. Axis troops would practically checked every corner here and there, and didn't show much mercy. One of the Axis primary weapons was the MP40, A sub machine gun with 32 bullets per mag, powerful and with low recoil for a WW2 weapon.
He was actually elected chancellor of Germany, Czechoslovakia didt fight back, and many tactical things like blitzkrieg, which is where 3 main forces attack at once to overpower, usually one air, one infantry, and one tanks
His tactic of "blitzkrieg" or "lightning war" involved rapid attacks specializing in fast moving tanks and transports which were decades ahead of those they were attacking. They were supported by equally advanced aircraft, weapons, and training. Their superior numbers overwhelmed their enemy and were able to rapidly advance
It was like a bear attacking a lamb, the countries he blitzed in the beginning had little defense, the first, Poland, hardly fought back. His plan was to incorporate these defeated countries into his Army, make them fight for Germany.