What is the attack sequence?

The attack sequence goes like this. All move together. Check range, check speed, check defender if speed tied. Therefore both will move forward, if both in range, they will check for speed for who attack first. If speed tied, defender will always go first. Now let's say that a cav army want to attack a cat army, at first glance, the cav is in range to attack, but the cat move backward. Therefore, cav range lost, speed lost, therefore cat will attack first. This hold true even if the cat have slight lower speed. They can still move out of range.

Are you sure?
Cuz most of the time, they generate the same result. Are you sure its all move all attack not one move and attack then another?

I'm positive during each round all moves are done before any attacks.

Both teams move at the same time

Check your war reports...

The one with the highest speed (defender if tied) moves to its max range, then the opponent moves. This is shown if both have long range cavs and the the one with the higher speed will still move as far as they normally do, they don't meet at the half way point. Then the higher speed (defender if tied) will attack first.

they move at same time, one reaches it first and fires first