The intent in each of those cases was to terrorize civilian populations as way to force a surrender.
I would argue with this assertion. Sherman did not engage in rape and wholescale slaughter (the usual terror methods in war), rather he sought to destroy the economic base that supported the Southern war effort.
In the case of Hiroshoma and Nagasaki, the terror of the civilian population was not the point as they had no say in matters. Rather it was to convince the leadership that not only were they going to lose (they knew that already), but if they didn't surrender, there would be nothing left.
Bringing cases of full-scale war into the discussion confuses the picture imo since terror is a traditional component of warfare. This doesn't mean that terrorism has no meaning, just that the term usually doesn't make sense in the context of two economies waging modern total war.
There are still many methods for obtaining political ends short of full scale war: politics, persuasion, civil disobedience, extortion, riots, guerilla war, terrorism, etc. It is when a group chooses terrorism out of this list of methods, especially when they had other options and could have chosen other methods, that they can clearly be called terrorists.
What is the Red Tent? |