Why did the pope give his blessing for William of Orange to go to war with James II and Louis XIV?

William of Orange was actually known by two names at this period of time, which can make it difficult to be sure if you're reading on the right person in various scripts. He was known mainly as William III of Orange (being his Stadtholder, or his regal title for his presidence over Dutch/Holland/Zeeland rule) but he was also written as William II of Orange (which was his title as King of Scotland presiding over England and Scotland during the abdication of James II). However, the locals called him King Billy...

SO to answer your question, the Pope never gave a blessing for William III of Orange to go to war with James and Louis. In fact, quite the opposite was the case. James II (as well as Louis XIV) was a strong Roman Catholic and was fighting to give more power to the Roman Catholics in England and Ireland. Most of his army was Irish Roman Catholics (even after he abdicated the throne the Irish still fought King Billy until he conceded their rights along with the Jacobites).

The Vatican was unhappy with the success of the Protestant William and his wife Mary II to be ruling the nation of England for the short time after James II.