Help: Translating Napoleon

[Nikaïa's tyrannos]

Cet Annibal... qui ne descend en Italie qu'en payant de la moitie de son armee la seule acquisition de son champ de bataille, le seul droit de se combattre.'

If I may help (I'm French)...

'This Hannibal... who came in Italy buying with half of his army the single acquisition of his battlefield, the single right to fight.'

I can assure you that, even for me, this sentence is barely understandable at the first glance.