From this article in The Atlantic:
Pervitin was the early version of what we know today as crystal meth. And it was fitting that a German soldier would become addicted to the stuff: the drug, Der Spiegel notes, first became popular in Germany, brought to market by the then-Berlin-based drugmaker Temmler Werke. And almost immediately, the German army physiologist Otto Ranke realized its military value: not only could the methamphetamine compound keep fighters (pilots, in particular) alert on little sleep; it could also keep an entire military force feeling euphoric. Meth, Spiegel puts it, "was the ideal war drug."
And it was, as such, put to wide use. The Wehrmacht, Germany's World War II army, ended up distributing millions of the Pervitin tablets to soldiers on the front (they called it "Panzerschokolade," or "tank chocolate"). The air force gave the tablets to its flyers (in this case, it was "pilot's chocolate" or "pilot's salt"). Hitler himself was given intravenous injections of methamphetamine by his personal physician, Theodor Morell. The pill, however, was the more common form of the drug. All told, between April and July of 1940, more than 35 million three-milligram doses of Pervitin were manufactured for the German army and air force.