Adolf Hitler was intoxicated with drugs—nearly all of them. Throughout his reign of terror, he shot up anything from steroids to heroin before sending Nazis 35 million pills of meth—on one occasion alone.

The fact, long discussed in Nazi lore, has resurfaced with new details in a book out Thursday by German writer Norman Ohler titled Der Totale Rausch (The Total Rush). Ohler, an award-winning novelist and screenplay writer, spent years sifting through German and U.S. records to uncover more details about the Fuhrer’s drug-induced genocide, which led to the death of six million Jews.

To keep up with Hitler’s fast-paced killing machine, Nazis relied on what was essentially a pill form of crystal meth, called Pervitin. Synthesized by a chemist in Berlin and marketed for alertness, the drug was initially sold over the counter in pharmacies across Europe. Just one pill, says Ohler, gave the Nazis the alertness they needed to remain awake for hours. Thanks, in part, to the ease with which they could obtain it, the Nazis believed it to be just “like coffee.”

A major report in Der Spiegel from 2005 initially told the story of how the drug was initially introduced to the German military force (Wehrmacht) after a military doctor’s experimentation of it on 90 college students led him to the conclusion that it would “help win the war.” Less than six months later, millions of the pills were flown to the front lines and handed out to the Nazis before invasions.

Overtime the habit turned to an addiction, as evidence in letters from the time. In November of 1939, one Nazi in Poland sent a letter to his family with a note that read: “It's tough out here...Today I'm writing you mainly to ask for some Pervitin.” Six months later, he wrote again: “Perhaps you could get me some more Pervitin so that I can have a backup supply?" Then two months later: "If at all possible, please send me some more Pervitin.”

Ohler says the drug was used specifically for Blitzkreigs, including the invasion of Sudetenland, Poland, and France. The Nazis found Pervitin effective at keeping them awake for “days at a time,” allowing them to hike as many as 36 miles in a day.

Their use of the drug was no secret, at least in the beginning. Ohler found British press at the time glorifying the drug as a “miracle pill.” While use of the drug began to diminish once it was outlawed in 1941, Ohler spoke with one general who said it continued much longer.

It’s unclear whether or not Hitler used meth, but Ohler suggests he didn’t use Pervitin. If so, it was one of the few things he didn’t try. Based on the personal notes from Hitler’s own physician, Dr. Theodor Morrell, Hitler was “ceaselessly” injected with doping agents, dubious hormones, and hard drugs. By the time of his last offensive in the winter of 1944, Hitler had “long known no more sober days.”

Meth undoubtedly played a role in the Nazi’s ruthless and murderous rampage, at first flooding their brains with serotonin and dopamine, then later (when it began to wear off) sending them into fits of severe irritability, anger, and rage. Hitler’s use of heroin could have done even more damage. Entering his bloodstream near-instantly, the drug would have delivered him a rush of euphoria before spiraling him into a bleary-eyed state of delirium. But when the drug’s effects wore off it would give way to profuse sweating, severe agitation, and uncontrollable anger.

Both drugs cause significant long-term damage—specifically neurological. Continued use of meth can lead to mental deficiencies, aggressive behavior, and psychosis. Chronic use of heroin has been shown to deteriorate the brain, impairing decision-making and fueling irrational responses to stress.

But while other armed forces have been known for using drugs, it’s Hitler’s rampant drug use that Ohler says shocked him the most—an addiction that he says led him to “maintain his delusion until the end.”