Position the spoils of war as just reward for defeating the cursed enemy.
Celebrate the victors and the brave. Make taking of the spoils of war a glorious thing.
Yet also beware of the damaging effects of extrinsic motivation. When the spoils of war become the main motivation, soldiers lose focus.
Ensure your troops do not become as animals, for example by sustaining humanity in the treatment of prisoners. When the enemy’s possessions have been taken, the person may be forgiven.
Soldier who are captured and abused will hate you forever, as will their friends and family. Treat them well and they will take your part more easily. Doing this also encourages your enemy to likewise.