One of the things we should remember is this- the Protestant Reformation didn't start until AFTER the Christians drove the Muslim heathen from most of Europe. Now, for the first time since the Reformation, we're facing a Second Islamic Invasion of the world, and it's now time for Catholics and Protestants to see what they have in common (worship of the Savior Jesus Christ), downplay the differences, and fight the common enemy.
The Battle of Tours, the Reconquista and the overthrow of the Emirate of Sicily all occurred before the Reformation.
The siege of Vienna, the Battle of Lepanto and the Great Turkish War all occurred after the Reformation, and were characterized by the refusal of the Protestant powers to aid the Catholic and Orthodox powers in their struggle.
Hey and guess what? Since we have actually been talking to each other, we've found that most of what we "knew" about each other before was wrong.