http://www.mangapanda.com/one-piece/727

A flashback reveals how the people hated the Riku kingdom. Doflamingo appeared to buy the country but Riku wouldn't allow it. He asks the kingdom to give them all the money they had to keep this kingdom. However Doflamingo uses his powers to make the king and all his soldiers attack the people, for when people are in true fear, a "hero" will appear.