What happen in world war 2. who cause the world war 2. and what kind of technology stuffs did they use for the world war

1: War, War, War, Allies win.

2: Germany and Russia,

3: A good amount aside from the nuke.

Explanation

World War 2 is the most costly war in the history of mankind with websites estimating total loses worldwide between 60 and 120 million lives lost including soldiers, civilians, and prisoners. Germany and Russia caused WWII on September 1, 1939 when both nations invaded Poland from both sides, Russia with overwhelming force, and Germany with their new Blitzkrieg strategy.  Some technology that was invented that are rarely mentioned are the use of air systems and parachutes for aircraft first being used in combat, Thruster powered aircraft (Jets), and a recoil operated muzzle booster that helped make the MG 42, (aka Hitlers Buzz Saw) the most dangerous firearm to fight against. This mechanism paved the way for how firearms are made today with an average RPM, (Rounds Per Minute) rate for the MG 42 at a jaw dropping 1,200-1,600 RPM, over twice the fire rate as the American M1919 at only 400-600 RPM. Hope this helps.