Regardless past or present, war is something that nobody will wants, because it takes away innocent lives due to it's unchanged characteristic, violence and killing. However, war does changed and evolved into a more and more serious disease to humans, which the wars nowadays will cause much more deaths than the past due to the advancing technology.
1) Weapons
In the past, people uses sword, bow and arrows to fight. With the advancing technology, cannons and guns are introduced into the battlefield by the Europeans. Lastly, the scariest weapon was invented by U.S and it bombed Japanese cities of Hiroshima and Nagasaki 6 and 9 August 1945 - the atomic bomb. From what we can see, the weapon has become more and more powerful as the technology advance. Thus it simply causing more deaths than the present, and a more serious disease to the human race.
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2) Manpower needed
In the past, war comprises mainly of physical kills and manpower. However, in the present, with the help of the technology, less manpower is needed due to the advancing weapons which requires lesser manpower while dueling much more damage to opponent. War happening now is mainly of chemical weapons like guns and bombs. For quick reference, if assuming that a single manpower can cause 1 death, a sword can cause 2 deaths, a cannon can cause >1,000 deaths, and an atomic bomb may cause around 100,000 deaths (90,000 ~ 166,000 deaths in Hiroshima and 60,000 ~ 80,000 deaths in Nagasaki). This shows how the weapons has replace the manpower needed in war.
