Certainly new technology and unprecedented populations were major aspects of warfare during this time period. I would add poison gases to your list. Remember t

Certainly new technology and unprecedented populations were major aspects of warfare during this time period. I would add poison gases to your list. Remember though that many other (non-destructive) technologies made their entrance during these wars: blimps, new classes of naval vehicles (the so called battlecruiser) and also submarines, precision bombing, new types of artillery, the first tanks, trains for transporting goods and troops, radar... And remember that the tactics of the time changed as much or more than the technology. In WWI a prevailing tactic was troop attrition - the infamous Battle of Verdun being a sick but paragon example. WW II saw the advent of the term 'strategic bombing' which in essence was the idea that if you directly kill huge numbers of civilians it will demoralize the enemy, cause them to withdraw, and end the war faster - in the end supposedly saving lives. Of course it didn't work out that way, but the belief that it would contributed to the constant bombing raids and huge civilian bombardments that WWII was famous for.