A shocking documentary is shedding new light on just how far the Nazis and Allied soldiers went in an attempt to win World War II — including the use of performance-enhancing drugs.

"Secrets of the Dead: World War Speed," which airs June 25 on PBS, reveals that Nazi soldiers were given the methamphetamine Pervitin, manufactured by Temmler Pharmaceutical, while American and British forces used everything they could get their hands on, including coffee, Pervitin obtained from Nazi forces and the amphetamine Benzedrine.

"In 1940, the British army discovered Pervitin in a downed German plane in the south of England, unlocking the secret to the German troops’ boundless energy, and leading the Allies to consider the same tactic for their troops," PBS representatives wrote in a statement.