The start of a war is not accomplished in a single move, nor can the decisive battle begin right from the outset.
At least, this was the case for the war faced by Alexander, Orion, and Isabella.
Aside from a portion of undead left behind to resist the enemy and buy more time for the transfer, the allied forces of Alexander and Isabella were moving south at full speed.
"We don't have much time. Without anyone to command them, the number of undead troops in the rear will dwindle, and the enemy will soon notice something is amiss."
Alexander, Orion, and Isabella each rode on beasts similar to unicorns, creatures native to Isabella's world.
In Isabella's world, every lord raised a large number of cavalry. Cavalry of all sorts were the defining feature of her world.
The term "mounted charge" could perfectly describe Isabella's world.
This was also why Isabella, despite being a woman, could become a Dragon Knight.