Work with gravity; running uphill is harder than running downhill.
The time to ascend is before the battle, so that you have clearer vision of the enemy. You can see what direction he is coming from, how large the army is, what weapons they are using.
A good example of this is Chamberlain at Gettysburg. His men ran out of bullets. He ordered them to rush downhill in a bayonet charge. He won the battle.