Next round you'll need to make a DC20 Ride check to control your mount though (http://www.d20srd.org/srd/skills/ride.htm, see Control Mount in Battle).
So what gets around that? Does it need the Combat Riding set of tricks specifically? Does it have to be specifically a warhorse (or other mount with "war" in the name)? Since I assumed my mount is trained somehow, I put down that it has the attack trick twice, which means it will attack undead, aberrations, etc. I don't think I've ever actually used a non-warhorse mount in combat before, except for ones that weren't trained to fight at all (which I just dismounted from).
Yeah, I had to look it up as well. I think the Combat Riding set should do the trick, yes.
Ok. Mind if I change the mule's tricks to "Combat Riding" package, then? I just thought some of the tricks in that set looked utterly worthless and/or redundant, and wanted to replace them with more useful ones like tracking, working, etc. I figured that giving it attack twice, so it will fight things like aberrations and undead, should be enough to make it not "frightened" in combat... I mean... if it will attack a Spawn of Kyuss when told to, it obviously isn't that frightened... or can overcome it, at any rate...
But... mules are cheap. I can just buy one to carry my shit around, track, etc, and another one as a "war mount".
Either way is fine. I can just dismount, also.