The powerful Jem'Hadar soldiers were the military muscle of the Dominion. The Founders controlled the Dominion, but they used the Vorta to administer their rule. There's no doubt that the deadly Jem'Hadar would have defied the Vorta, if the Vorta hadn't kept the Jem'Hadar addicted to the drug known as ketracel white. This ark was used by the Vorta for the ceremony in which the drug was distributed, reinforcing the Vortas' control over the warriors.