Wouldn't it be more separated and the defenses left in tatters as you have armies and garrisons loyal to the previous king and other armies and garrisons loyal to the current king? Really? That is idiotic.
Most don't even realize there is a new king. He still goes by "Caliph Zebulen" and most likely Zebs son tricked everyone into thinking his father died of natural causes. He was quite old. They either think it's the same Caliph or the old one died and his son stepped up. Regardless, rebellious soldiers are killed on spot
Still, how do they magically double their defenses? There is no logical process that they could have used to do this. Did they summon magical soldiers out of nowhere?