The Thirty Years’ War refers to a series of armed conflicts in central Europe between 1618 and 1648. It was one of the longest and most destructive wars in European history. The war can be divided into four phases: Bohemian-Palatine (1618–1625), Danish (1625–1629), Swedish (1630–1635) and French (1635–1648). Some historians recognize the existence of a fifth period in addition to the four canons: the “Italian period” (1628-1631), corresponding to the war of succession of Mantua and Monferrato.
Started as a war between Protestant and Catholic states in the fragmented Holy Roman Empire, it developed into a more general conflict that involved most of the great European powers, losing more and more of its religious connotation and becoming better part of the continuation of the Frankish rivalry.
The war began when the Holy Roman Empire . The Protestant states of the North, outraged by the violation of their rights acquired in the peace of Augusta, united forming the evangelical union. The Empire immediately opposed this league, perceiving it as an attempt at rebellion, provoking negative reactions from all over the Protestant world. Sweden intervened in 1630, launching a large-scale offensive on the continent. Spain, wishing to overthrow the Dutch rebels, intervened under the pretext of helping its dynastic ally, Austria. Fearing the encirclement by the two great powers of the Habsburgs, Catholic France joined the coalition alongside the German Protestant territories to oppose Austria.
The war, characterized by very serious and repeated devastation of inhabited centers and countryside, by mass killings, by military operations conducted with ruthless ferocity by mercenary armies often protagonists of looting, as well as by deadly epidemics and famines, was an epochal catastrophe, in particular for the territories of central Europe. According to the academic Nicolao Merker, the Thirty Years War, which would have caused 12 million deaths, was “by far the greatest catastrophe ever” on Germany.