His Red Eminence, Armand Jean de Plessis de Richelieu was not only a French clergyman but a noble and the Secretary of State, King Louis' (and the world's first) Prime Minister until his demise in 1642. Cardinal Richelieu sought to dominate domestic factions; including restraining the power of the nobility in an aim to consolidate all power for the King (ie. French Royal Power). Most of Europe was already preoccupied by the Thirty Year's War long before Richelieu's rise to power. France and Richelieu were alarmed by the absolute power and influence shown by Emperor Ferdinand the II over his Protestant opponents in Germany in 1629. This directly threatened his concepts of concentrated French Royal Power. Thus, siding with the protestants served their immediate political power needs more than it offended their Catholic sensibilities. This data is verified via Wikipedia etc. .