[Gandalf Parker]

The power of Caelum is in the flight. Going head-2-head as if you are both playing Ulm is not in your favor. You can jump over his armies and hit the provinces behind his front line. You can send sneaking priests in to lower his dominion and look for backside provinces that have low defense. You can position all of your armies far back on the battlefield forcing his to run forward seperating his infantry from his rear units, then attack rearmost or archers (use troops assigned to guard a commander that is told to shoot/shoot/attack-rear)

Also "Call of the Winds" is cheap. It can soften a province you are about to attack, it can keep him on his toes in the back areas, it is great for casting onto any high-gold province of yours for patrolling so you can tax higher. If you do the Last then you can switch the flyer-units to a cheap indept commander and use the leader as another flying commander such as with the hold-then-attack-rear tactic mentioned earlier.