Which makes me think the NA & EU ads messed up. That the ad wasn't supposed to advertise the upcoming battle on the 24th, it was supposed to advertise the special 45 minute event.
e: Man the Cavalry mission is such a pain. There's so much that can go wrong. Infantry is a breeze because you get access to just about everything. Bows, Daggers, Healers, mages of all types, dancers (!), the full weapon triangle with a laundry list of good units. Assuming you have enough at high level its pretty easy to switch around and find a good team that works for you.
Cavalry are in general more limited, primarily physical, and the horse mages & healers are in shorter supply and general not as good (To make up for having a horse). It is really easy to get stonewalled by armors (or worse, DOUBLE HECTORS WITH A HEALER)