• We have updated our Community Code of Conduct. Please read through the new rules for the forum that are an integral part of Paradox Interactive’s User Agreement.
Cavalry does give you a bonus during the shock phase of combat if you have a 2-1 advantage. I sometimes pursue broken armies out of my province. If I have cavalry detachments, I can frequently catch them before they leave my province and wipe them out
 
And early in the game, when you have large cavalry-armies and enemy doesn't have guns, you can completely wipe out entire enemy units. When guns come, it takes a bit more of the cavalry to do the job....