Answer:
The idea was to win faster than the defending side could react / mobilize the troops.
blitz means lightning in german.
Rushing forward and living off the resources of the countryside (basically looting and stealing from the people)
the strategy falls apart when warfare takes longer than expected.
but the early successes of the Nazis may also be due to the fact that some defendants still used horses on the battlefield.
Thankfully the strategy fell indeed apart when the Nazis decided to advance into Russia