War is nasty business. I know that there was some region in German in which only something like 900 people survived the war. As I recall, and you can correct me, Richleieu, a Catholic, supported Sweden against other Catholic states.
You are correct. Richelieu was a consummate machiavellian. Indeed, the Catholic French kings have a long history of what you might call fighting on the wrong side. They supported the Protestants because they wanted to weaken their chief European rival, the Holy Roman Emperor.
More egregiously, a number of French kings allied with the Sultan of Turkey, for the same reason, because they wanted to weaken the Empire, and in the case of Louis XI, to suck the former Duchy of Burgundy into France.
But while French Catholic kings supported Protestants abroad, at the same time they persecuted the Huguenots in France. And Richelieu conducted the expulsion of England from Calais.
"War is nasty business. I know that there was some region in German in which only something like 900 people survived the war. As I recall, and you can correct me, Richleieu, a Catholic, supported Sweden against other Catholic states."
France was under the threat of becoming encircled by Habsburg regimes (and their allies) and therefore She allied Herself with Sweden which was aiming to control Northern Germany as well as The Baltic Sea.