Private Manning was the only whistle blower. Everyone else kept quiet because they were told to. Civilians, Military personnel, it did not matter. Everyone kept quiet except for one person because the authority told them to.
By the way, even though Manning will likely die in prison, the conspiracy went even farther by turning him into a girl. Damn bastards have no end to their cruelty for talkers. It seems to make it that much easier to control the others who have knowledge that they do not want to be leaked.