30 Years' War: 1618 to 1648 by Samuel Gardiner

One of the most complete histories of this inter-Christian war, fought mainly in the heartland of present-day Germany, in which up to 40 percent of the population was killed.

Written not as a dry history but rather as a highly-engrossing story, this classic work—which set the standard for all later histories—starts with an explanation of the religious conflict between Catholic and Protestant in Germany, and explains how this dispute then spiraled out of control into what became the most devastating European war of all time.