Due to the deaths of Gustavus Adolphus and Wallenstein, as well as by exhaustion on both the Holy Roman and German Protestant side, The Treaty of Prague in 1635 brought an end to the Swedish period of the war, weakening the German States, and strengthening the Hapsburg empire. Cardinal Richelieu, who was the chief minister of King Louis XIII of France, secretly plotted against Phillip IV, intending to weaken the power of the Hapsburgs and take the province of Alsace from the Holy Roman Empire and had been intervening in the war through financial or resource aid to Sweden and the Netherlands . France had held back form direct military invovement in Europe, however, when Spanish troops marched into Trier, a German state under French protection, and captured the Archbishop Elector, France declared war on Spain. In May 1635, France declared war on Spain. In October 1634, the Holy Roman Emperor, King of Spain and the Roman Catholic princes of Germany had agreed to a joint attack on France. Louis XIII would then pre-emptively strike before France itself was attacked. Though it got off to a poor start, the French
army would eventually drive Spanish and Austrian armies back across German states. The Battle of
Rocroi in 1643, was the first defeat of the Spanish army in over a century, and could be considered a turning point in the war.
For some time, Holy Roman armies, aided by catholic princes, succeded in holding their own against the Swedes and German Protestants. A series of french successes against Spain enabled the French to send larger forces into Germany.
Emperor Ferdinand II died in 1637 and was succeeded by his son, Ferdinand III. After which peace negotiations would begin in 1641, but made little progress until the death of Cardinal Richelieu in 1642 and the French occupation of Bavaria in 1646. Gradually the German forces were weakened, and France took control of Alsace and a large portion of the Rhineland while the Swedes took over much of northern Germany, and proceeded to carry out the war into Bohemia.
For some time, Holy Roman armies, aided by catholic princes, succeded in holding their own against the Swedes and German Protestants. A series of french successes against Spain enabled the French to send larger forces into Germany.
Emperor Ferdinand II died in 1637 and was succeeded by his son, Ferdinand III. After which peace negotiations would begin in 1641, but made little progress until the death of Cardinal Richelieu in 1642 and the French occupation of Bavaria in 1646. Gradually the German forces were weakened, and France took control of Alsace and a large portion of the Rhineland while the Swedes took over much of northern Germany, and proceeded to carry out the war into Bohemia.