One of the things many of us have come to internalize is the notion that the modern era - the 20th century in particular - was more brutal than any time that had come before. Reading Tuchman's "A Distant Mirror" has disabused me of that notion - there's a reason she used the subtitle The Calamitous 14th Century.
The book focuses on 14th century France (and in turn, on England, as this was during the span of the 100 year's war). The casual slaughter she documents is startling. The first thing you have to realize is that warfare was a different matter then - states only partially existed, and loyalty was to individuals - lords and the royalty. After a King raised an army, he had to figure out how to pay it (typically via harsh taxation of the already poor peasantry). Woe betide the countryside if the army survived until "peace" was declared - many of the nobles who raised armies took to a life of rapine and pillage once peace came. It was bad enough in France after the black death hit in 1349 - the various companies of soldiers who were no longer fighting for the French or English in the wake of that catastrophe took to raiding the countryside.
One thing she documents is that the population of France may have dropped by half between 1300 and 1400 - due to plague, the 100 years war, and banditry. An absolute eye opener...