The Thirty Years’ War

The religious conflicts in Europe that started after the Reformation continued into the 1600s. The Thirty Years’ War began in 1618 as a protest by the Protestant noblemen of Bohemia (now part of the Czech Republic) against their Catholic rulers, the Holy Roman emperors.

Bohemia’s nobleman chose Protestant Frederick of Bohemia to become their king. Then, in 1619, Ferdinand II, a member of the powerful Habsburg royal family, became the new Holy Roman emperor. Ferdinand was determined to return the entire Holy Roman empire back to Catholicism, so he sent his army to attack the state of Bohemia in order to overthrow their new Protestant ruler and replace him with a Catholic one.

By 1620, Ferdinand’s army had defeated Frederick’s troops, forcing him and his family to flee to the Netherlands, which was largely Protestants. Catholicism was now the only form of Christianity allowed in Bohemia. At this time, Spain was also ruled by members of the Habsburg family and, in 1621, they joined the war on the side of the Holy Roman empire and sent an army to fight against the Protestant Dutch. In 1625, the Dutch turned to Denmark and England for help and both countries sent forces. Many English soldiers were killed not by fighting, but from plague. Many English soldiers were killed not by fighting, but from plague. Just four years later, in 1629, Habsburg armies had also defeated the Danes.

The Protestant Swedish king Gustavus II Adolphus led his army to war against Spain and the Holy Roman empire in 1630. He won in Saxony at Breitenfeld in 1631 and again at Lutzen in 1632.

However, Gustavus was killed during a cavalry charge at the Battle of Lutzen when he was separated from his own forces. Two years later Sweden withdrew from the war.

Finally, France entered the war in 1635. Even though it was largely a Catholic nation, France joined the Protestant side in order to weaken the power of the Habsburg family in Europe. At first, Spain was victorious, but from 1637 the French and their Protestant allies were able to defeat them. The Treaty of Westphalia ended a war that, together with disease, had halved the populations of many German states.