Thirty Years' War , a series of European conflicts from 1618 to 1648, fought primarily in Germany. The war started in Bohemia with a Protestant revolt against the Holy Roman Empire and eventually involved almost all of the countries of Europe. By its final years, religious issues had been submerged and it had become a struggle for power between Austria and Spain on one side and France on the other.

The war demonstrated that neither Catholics nor Protestants were strong enough to dominate the continent. Religious toleration was increased in Germany itself, but freedom of worship was still severely limited in all countries.

The Thirty Years' War radically altered the balance of political power among the countries of Europe. The Holy Roman Empire lost effective control in Germany, and the influence of the Austrian Hapsburgs, the hereditary emperors, was thus greatly reduced. France emerged as the dominant nation in Europe. Sweden, too, gained in influence. Spain's power and prestige declined greatly. Holland, which had broken away from Spain in the preceding century, was formally acknowledged as independent, as was Switzerland.

Germany, already divided into many semiautonomous states, became a patchwork of independent countries. In regions where armies had camped and fought, the devastation and loss of life were so great that some communities were permanently deserted.