During the CNN GOP Debate, Donald Trump gave two explanations for the repeated violent reactions of some of his supporters to protests at Trump rallies. The first one being love for their country and anger at the current state of it, the second being this:
We have some protesters who are bad dudes, they have done bad things. They are swinging. They are really dangerous and they get in there and they start hitting people, and we had a couple of big strong powerful guys doing damage to people. Not only the loudness — the loudness I don't mind — but doing serious damage.
There are others that dispute the claim that violence originated from protesters, see eg The Washington Post.
Is there any evidence for cases where protesters at Trump rallies have gone in "swinging" and done "serious damage" before the CNN debate?
As there seems to be some confusion about the claim, please note: The question is about a specific statement Trump made. Trump made the statement in March about the past, not about future events which may or may not happen. It wouldn't make sense for Trump to justify assaults by his supporters with future assaults by protesters, so any events which happened after March 10th 2016 obviously do not support Trumps claim.
When I'm using "violence", I mean physical violence in the case of protesters as well as in the case of rally attendees.
A list of violence by Trump supporters can be found here (I haven't checked if it is complete). The earlier dates on that list are 10/01/2015, 10/02/2015, and 11/21/2015. As Trumps statement is meant as an explanation or defense of violence by his supporters, to verify the claim, an incident of a protester starting violence before 10/01/2015 would be great. Still, any events from before the CNN debate - which was on March the 10th - would help support his claim. This also means that the person trying to jump the stage in Dayton or the events in Chicago would not verify the claim, as they happened after the debate.