But the ice-cream industry, still in its infancy, demanded even more for the boys overseas: not just calories, but comfort. An editorial in the May 1918 issue of The Ice Cream Review, a monthly trade magazine, spooned out sharp criticism for the scant availability of ice cream overseas: “If English medical men knew what ours do every hospital would keep ice cream on hand for patients.” It cried for Washington to intervene by subsidizing Allied ice-cream factories throughout Europe:

In this country every medical hospital uses ice cream as a food and doctors would not know how to do without it. But what of our wounded and sick boys in France? Are they to lie in bed wishing for a dish of good old American ice cream? They are up to the present, for ice cream and ices are taboo in France. It clearly is the duty of the Surgeon General or some other officer to demand that a supply be forthcoming.

The ice-cream industry didn’t have much lobbying power. Few Americans had refrigeration. Worse, Hoover had downplayed the scarcity of domestic sugar supplies, hoping to avoid a panic. There was hardly any sugar left for America, let alone for allies in France and England—and the promotion of ice cream as a wartime cure-all wasn’t helping. Instead of bolstering ice cream production, Hoover’s Food Administration ordered a reduction of manufacturing domestically—ruling in the summer of 1918 that “ice cream is no longer considered so essential as to justify the free use of sugar in its manufacture.”

That stance would change drastically during the next two decades, however—owing partially to the unlikely contributions of Prohibition and the Great Depression. When the 18th Amendment outlawed the sale of spirits in 1920, many early American breweries, including Yuengling and Anheuser-Busch, turned to soda and ice cream to stay afloat. By the end of the decade, Americans were consuming more than a million gallons of ice cream per day—and, crucially, associating it with the comfort and diversion formerly assigned to alcohol.

The ice-cream maker William Dreyer helped further this sentiment in 1929 when he marketed Rocky Road as a culinary metaphor aimed at helping people cope with the crash of the stock market. The term now refers to just chocolate with chopped nuts and chunks of marshmallow, but it used to be symbolic of comfort—a sweet indulgence juxtaposed with broken, “rocky” pieces.

When World War II hit, countries on either side of the conflict once again banned ice cream, with Britain adding insult to injury by endorsing carrots on sticks as a wartime substitute. But the United States doubled down. Ice cream had become inseparable from the American way of life—and, from that point forward, from military tactics.

In 1942, as Japanese torpedoes slowly sank the U.S.S. Lexington, then the second-largest aircraft carrier in the Navy’s arsenal, the crew abandoned ship—but not before breaking into the freezer and eating all the ice cream. Survivors describe scooping ice cream into their helmets and licking them clean before lowering themselves into the Pacific. By 1943, American heavy-bomber crews figured out they could make ice cream over enemy territory by strapping buckets of mix to the rear gunner’s compartment before missions. By the time they landed, the custard would have frozen at altitude and been churned smooth by engine vibrations and turbulence—if not machine-gun fire and midair explosions. Soldiers on the ground reported mixing snow and melted chocolate bars in helmets to improvise a chocolate sorbet.