The Roman Empire had the best military machine of its day, but this was not sufficient on its own to guarantee its survival. The Romans suffered decisive defeats in their homeland from both Pyrrhus and Hannibal in the 3rd Century BC that would have destroyed any contemporary nation. After winning, the victors expected the Roman ambassadors to arrive and sue for peace. Instead, what turned up was another Roman army.
How did they sustain this? As well as indomitable will, they needed the extraordinary loyalty of their Italian allies. Even with the Romans reeling, the allies contributed their manpower to call up another army and rarely defected.
What inspired this loyalty? As would be expected of ancient times, self-interest trumped more noble rationales. With the Italian allies, the Romans were generous in victory, creating an incentive system with 4 tiers of citizenship for allies to climb, with rich rewards at the top. The Italian allies simply saw their best future as partners of Rome.
The business equivalent is how a dominant player treats their business partners, their employees, suppliers and customers. In the good times, do you use your strong negotiating position to maximize your profits at their expense? Or do you create incentives that allow them to thrive too?
In tough times, do you expect them to stick with you, or embrace your attacker who can offer them a more attractive future?