I want to know the answer to the following question:
Which Battle was the first to interrupt the seeming invincibility of the Old Swiss Confederacy in 1515?
All the background I'm provided with is that "It was not until more than one hundred years after these internal wars that, in 1648, under the Peace of Westphalia, European countries recognized Switzerland's independence from the Holy Roman Empire and its neutrality.". Is that enough to answer the question?