8 Everyday Inventions That Came Out of Wartime

In 1943, a woman named Vesta Stoudt was inspecting ammunition boxes at an ordnance plant in Illinois, and she was worried. The boxes were sealed with thin paper tape and a little tab you were supposed to pull to get them open fast — except the tabs kept tearing, which is a terrible thing to discover when you’re a soldier under fire reaching for more cartridges. Stoudt had two sons in the Navy, and the problem wouldn’t leave her alone.

She sketched out the idea of a strong, waterproof cloth tape you could rip by hand. When her supervisors brushed her off, she wrote straight to President Roosevelt. The letter got forwarded to the War Production Board, which handed it to Johnson & Johnson, and the result was a rubber-backed, cloth-bodied tape built to be torn, not cut. You have Vesta Stoudt to thank the next time something in your house is held together with a strip of silver.

During World War II, a chemist named Harry Coover was trying to make a clear plastic for gun sights. The compound he and his team landed on — a cyanoacrylate — had one spectacular flaw: it stuck instantly to absolutely everything it touched, which is the last thing you want in a precision lens. They set it aside as a failure.

Years later, in the mid-1950s, Coover was at Eastman Kodak working on heat-resistant coatings when the stuff turned up again, and this time he saw it clearly. A glue that bonds in seconds, with no heat and no clamping, isn’t a flaw at all. It went on sale in 1958 as “Eastman 910,” and you now know it as super glue. The wartime goal was never the thing that made Coover famous — the accident was.

Radar won battles long before it reheated soup. By 1945, an engineer at Raytheon named Percy Spencer was standing near a magnetron — the tube that generates the microwaves a radar set uses — when he noticed a candy bar in his pocket had turned to goo. A less curious man would have grumbled and bought another. Spencer sent out for popcorn, aimed the tube at it, and watched it pop across the lab.

He went on to build a metal box with a door and a magnetron poking in, and the microwave oven was on its way. The first commercial model, the Radarange, stood nearly six feet tall and weighed about 750 pounds, so it wasn’t landing on anyone’s counter just yet. But the heart of the thing on your counter today is wartime radar, discovered by a melted chocolate bar.

This one needs the nuance. Alexander Fleming spotted penicillin’s mold-killing power back in 1928, and a team at Oxford proved it could save lives by 1940 — so the war didn’t invent it. What the war did was turn a laboratory curiosity, made in maddeningly tiny amounts, into a drug you could ship by the barrel.

The breakthrough happened in Peoria, Illinois, where researchers found that a mold growing on a cantaloupe from a local market produced far more penicillin, and that corn steep liquor made a cheap, rich broth to grow it in. Pfizer then cracked deep-tank fermentation, bubbling air through nine-thousand-gallon vats. By the D-Day landings in June 1944, the Allies had stockpiled enough penicillin to treat every soldier who might need it. The discovery was peacetime; the flood was war.

Long before the twentieth century’s wars, there was Napoleon, who understood that an army marches on its stomach and was losing more men to hunger and scurvy than to the enemy. In 1795 the French government offered 12,000 francs to anyone who could find a reliable way to preserve food for the troops.

A confectioner named Nicolas Appert spent fourteen years on the problem and claimed the prize in 1809 by sealing food in glass jars and boiling them. He had no idea why it worked — it would take Louis Pasteur decades later to explain the microbes — but it worked. Tin cans followed soon after. That humble can of soup in your pantry traces straight back to a general trying to feed a hungry army.

For most of the 1800s, a gentleman carried a pocket watch; a watch strapped to the wrist was considered a lady’s trinket. Then came the trenches of World War I, where fumbling a watch out of your tunic with one hand while the other held a rifle was a good way to get yourself killed. Timing mattered more than ever — artillery and infantry had to move together, often in the dark.

So watchmakers soldered little wire lugs onto small cases, added glowing radium numerals you could read at night, and the “trench watch” was born. Men came home from the war wearing them without a second thought, and the fashion stuck. If you’ve got a watch on your wrist right now, you’re carrying a habit that hardened in the mud of the Western Front.

Here’s a case where the Allies simply copied the other side because the other side had done it better. In the late 1930s, German engineers designed a 20-liter fuel container — stackable, with three handles so one person could grab two full cans, a flip-top spout that needed no funnel, and a recessed seam that let the metal flex without splitting.

Allied troops in North Africa got a look at captured German cans and realized their own flimsy tins were an embarrassment by comparison. They nicknamed the German design the “jerry can” — “Jerry” being wartime slang for the Germans — and adopted it wholesale. The red or green fuel can in your garage is very nearly that same shape, eighty-odd years later.

If you or a grandchild carries an EpiPen for a bee sting or a peanut, you’re holding a descendant of a Cold War weapon of a different kind. During those tense decades the U.S. military wanted a way for a soldier to jab himself with an antidote to nerve gas fast, through clothing, with shaking hands and no training in the moment.

An engineer named Sheldon Kaplan designed exactly that: a spring-loaded pen you press against your thigh. Kaplan then saw that the same gadget could save a civilian in anaphylactic shock, where seconds also count. That insight became the EpiPen, which reached the market in the late 1980s. A device meant for the worst day on a battlefield now rides in countless purses and backpacks, just in case.