ever see a live tree catch fire in California? of course you have there's always major fires everywhere in the summer, every fucking year. its on the news constantly. the trees are alive, and spreads to area where drought isnt nearly as much of a problem, thats some bullshit logic you got going on. especially when giant forest fires can and have been started by something as inconspicuous as a cigarette butt thrown out the window, into a ditch on the highway. and yes there was magic, there was also elemental fire. so yeah a couple catapults could easily burn that down.