Here’s the deal. Charles Emmanuel I the Duke of Savoy wanted Geneva’s wealth. Genevans wanted their independence. Many of them were religious refugees and would have had no where safe to go if Geneva had fallen to Catholic France. They also wanted to keep their money instead of giving it to the Duke.
The cannon was louder than the muskets. Unfortunately, there are not enough occasions where shooting off a cannon is permitted. If you can get away with it, it definitely says celebration (or attack). There’s also a race/run that takes place weekend of or preceding the night of the 11th It usually starts in the Parc des Bastions, where the Savoy troops congregated before attacking the walled city, and goes through Geneva’s old town, before finishing near the start. It’s a big deal here and everyone gets involved; you’ll even see families and running together. There’s even a youth race and a costume run.