The New Yorker has a good investigative piece on the history of the use of waterboarding by US troops in the Philippines in 1901-2 — a scandal that rocked the nation.
A letter by A. F. Miller, of the 32nd Volunteer Infantry Regiment, published in the Omaha World-Herald in May, 1900, told of how Miller's unit uncovered hidden weapons by subjecting a prisoner to what he and others called the "water cure." "Now, this is the way we give them the water cure," he explained. "Lay them on their backs, a man standing on each hand and each foot, then put a round stick in the mouth and pour a pail of water in the mouth and nose, and if they don't give up pour in another pail. They swell up like toads. I'll tell you it is a terrible torture."
And let us not forget: after WWII, Japanese soldiers who'd waterboarded their American prisoners were put to death by the US military for committing unconscionable acts of torture.