What an interesting topic. It is at the very core of why WWII was so ghastly and terrifying and has been correctly called the worst war in Human History.
While World War 1 was a war where 20 miles of movement by either side towards the other was in itself considered a victory, WW2 was a war were many tactics were employed by both sides, particularly in Russia. The army, navy and airforces made great strides in the use of technology even down to the systematic murder of many, many civilians.
