Accurately answering the question “What time is it?” has been a human obsession for millennia – but it’s only been since World War I that you’re likely to turn your wrist to do so.

Most societies, as far back as the Egyptians if not further, have had some mechanism for keeping time – sundials, water clocks, hourglasses – but those were fixed in place. By the 15th century, however, the development of the spring-driven clock meant that timekeepers could be freed from their moorings; there is some evidence of people wearing proto-pocket watches around their necks, a la Flava Flav. Through the 18th and 19th centuries, portable time-telling was largely the province of the pocket watch; if a timepiece appeared on a wrist, then it was a lady's wrist, and it was considered more a piece of jewelry than an item of function.

Exactly when the wristwatch was invented and by whom is unclear. The Guinness Book of World Records gives luxury watchmakers Patek Philippe credit for the first wristwatch, designed for the Countess Koscowicz of Hungary in 1868. But the venerable Guinness has been known to be wrong before, and there are records of other bracelet-style watches that pre-date the Patek Philippe model, including one designed and manufactured by Breguet for the Queen of Naples in 1810 (well, ordered in 1810 – it wasn't delivered until 1812). Queen Elizabeth I was supposed to have been given a watch set into a bracelet by Robert Dudley in 1571, which would have made her vastly ahead of fashion, but the item hasn't survived.

In any case, the ladies' wristwatch, often called a "bracelet watch", a "montre bracelet", or a "wristlet", existed for at least a century, if not longer, before its widespread adoption by the general public and by men at all. Why? Firstly, watches were still somewhat delicate and a timepiece on one's wrist could be guaranteed some shocks; these wristwatches, dripping with precious stones, were absolutely fashion first and function second. That they were so delicate probably reveals more about the women who were wearing them – that they may have been perceived to be as ornamental as the watches themselves.

Which makes it a little ironic, then, that what really drove the design and adoption of the wristwatch was war.

Accurate timekeeping is essential on the battlefield. "You can track back a number of errors in war to timing," said military historian Peter Doyle, author of The First World War in 100 Objects. But a pocket watch, however accurate it was, was somewhat unwieldy, especially as styles of warfare shifted from the Napoleonic – two armies facing off on a large field – to modern artillery-heavy, sometimes guerilla warfare. The first wristwatches designed for military use actually came in 1880: After one of his naval officers complained to his superiors that timing bombardments was too difficult with a pocket watch, Kaiser Wilhelm I commissioned Swiss watchmakers Girard-Perregaux to design and manufacture a watch mounted on a wrist strap. The Girard-Perregaux watches weren't terribly different from how wristwatches appear now, with the exception of the thick metal grill protecting the glass face. Though the wristwatches were indeed more practical in battle conditions, they weren't popular with men in the main and the design was discontinued. Roughly 20 years later, wristwatches were adopted by soldiers fighting in the Boer War in South Africa – some sported leather wrist straps into which a gentleman could put his pocket watch – but again, they didn't receive widespread attention. Even at the war's end in 1902, a redesign of the British officers' uniforms still came with a pocket for their pocket watch.

The problem was twofold: Firstly, wristwatches weren't considered to be as reliable as pocket watches, owing to the fact that they were jostled about a good deal more. And secondly, wristwatches, though practical, still had the whiff of womanliness about them: "The sort peer pressure would be, 'Why are you wearing that, that's a woman's thing,'" explained Doyle.

It would take a global war to catapult the wristwatch onto the arms of men the world over. Though the wristwatch wasn't exactly invented for World War I, it was during this era that it evolved from a useful but fringe piece of military kit to a nearly universal necessity. So why this war? Firstly, the development of the wristwatch was hastened by the style of warfare that soon became symbolic of the First World War: The trenches.

"The problem with the pocket watch is that you have to hold it," explained Doyle. That wasn't going to work for the officer at the Western Front – when an officer lead his men "over the top", leaving the relative safety of the trenches for the pock-marked no man's land in between and very possible death, he had his gun in one hand and his whistle in the other. "You haven't got another hand in which to hold your watch."

As in the Boer War, some men had taken to strapping their pocket watches to their wrists, but this was cumbersome and heavy. At the same time, technological advancements were making hardier timepieces. Several watchmakers, including Cartier and Rolex, had already been experimenting with watches that strapped to the wrist; Cartier, for example, had already begun marketing a watch that the company's principal, Louis Cartier, designed for Brazilian aviator Alberto Santos-Dumont in 1911 (Cartier still makes and sells a version of the watch). These watchmakers – and many others, including Omega and Longines – saw their moment and began manufacturing watches specifically for the military market. Indeed, the first use of the word "wristwatch" in paper of record The New York Times, is in a 1915 report from the annual meeting of the National Retail Jewelers' Association, which featured a presentation of wristwatches "for soldiers" with radium dials "so that the soldier can tell the time in the darkest night", as well as a compass. (Notably, subsequent mentions of "wristwatch" in The New York Times over the next few decades refer primarily to them being stolen.)

As the war ground on, more and more officers adopted wristwatches. "It's small, portable, it's essential, it's important," he said. "The wristwatch became something that men would wear because it was practical."

But if wristwatches are emblematic of the practical, functional evolution of military dress in the First World War, they're also emblematic of one of the lesser known aspects of the war: the merchandising. We don't often think of war as an opportunity to sell – it seems vaguely unsavory, however common it is – but manufacturers during the First World War certainly did. Doyle explained that retailers would often slap the word "trench" on items from coats to cookers, believing rightly that the association with the war would help sell. Sometimes manufacturers would label these new wristwatches "trench watches".

"Everything from 1914 onwards becomes 'trench this', 'trench that'… it's kind of a marketing ploy," said Doyle. Often, these items were marketed towards the families of men serving at the front and implied that whatever it was, it could somehow protect or comfort them. "You get all the wristwatch manufacturers – 'Just the thing for the man in the trenches.'" That context – the families on the home front just looking for something, even a sham talisman, that could make their boys safe – makes the symbolism that wristwatches also began to take on all the more poignant. Doyle owns a wristwatch that was taken from the body of a fallen soldier, buried at the front, and returned to his family as evidence of his death. "The broken remains of that soldier came down to this simple watch that was returned," he said. "This was physical evidence of the loss of this missing solider… He became a dead soldier and the family could mourn."

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After the war, wristwatches remained on men's arms. This was in part due to the fact that a global war meant global exposure, and partly due to the fact that the wristwatch was actually useful. Equally important was the kind of action man association wristwatches now carried, fully eclipsing the earlier associations with women's jewelry. Wristwatches were worn by aviators and explorers, men who didn't have time to pull out a pocket watch; this kind of imagery was intensely attractive in the years after the war. Later improvements to wristwatch designs and mechanics, including quartz movement, meant that watches were increasingly cheaper, and more widely available, even as luxury watches became even more, well, luxurious.

For the rest of the 20th century, wristwatches became so entrenched in the way people live that you can point to your wrist with a questioning look and be reasonably assured that someone will give you the time. Although these days, they might not get it from their watch – if you've got a phone, then you've got the accurate time (and yes, it is a little regressive that we use our phones like pocket watches now). But that doesn't mean that the wristwatch is on the way out. Sales of traditional watches did dip during the recession, but have since rebounded in a big way, driven mostly by sales of luxury labels.

We're also asking more of our watches, reimagining them in new ways; the most obvious of them being the smartwatch, which, though exciting, has yet to deliver on its hype (do you know anyone who has one?); Apple is expected to release its Watch this year, however, so maybe its time has come (sorry). But that's only one avenue – consider wrist-mounted quadcopter, Nixie, which will make your Inspector Gadget costume even more awesome this Halloween. As long as wristwatches retain that usefulness, that practicality, and maybe do some exciting things beyond telling time, why shouldn't they be around through the next world war?

Top image: Early wrist watch by Waltham, worn by soldiers in World War I. Deutsches Uhrenmuseum CC 3.0 de