Of all the inventions to emerge from WWI that are still in widespread use today – zips, trench coats, paper tissues, sanitary towels, stainless steel – perhaps the most unexpected is a dainty luxury wristwatch from probably the world’s most famous jeweller.

That the war kick-started the popularity of wristwatches generally is much easier to understand. With advances in artillery, aerial warfare and a much greater need for coordination than ever before, officers, airmen and infantrymen alike needed a hands-free timekeeper. But the watches used by the military were a far cry from Mr Louis Cartier’s groundbreaking design.

The origin story of the Cartier Tank is so well-worn we tend not to dwell on it, but to recap: this simple rectangular case with its thick bars (known as brancards), which extend past the dial to act as lugs for the strap, takes its outline from the first tanks rolling over the fields of Flanders. (There’s something of the field stretcher to it as well, perhaps.) Apparently, Louis Cartier was so affected by these terrifying weapons of war that he turned them into an elegant dress watch, a sleek icon of sophistication beloved of aesthetes, not armies.

When you really think about it, it’s a fantastic leap of imagination. To look past the rivets, tracked wheels and guns and see the purely geometric appeal of the massive, brutal shape, and then to realise that if correctly rendered (in yellow gold, naturally), it would take on a cultured form worthy of the Cartier name.

A century-and-change later and the Tank is one of the most recognisable of all watch designs, one of the most enduringly popular, and one of the most versatile. Louis Cartier’s original idea proved remarkably elastic, leading to Tanks of all shapes and sizes down the years.

The Tank deserves to be held up as a true icon of watchmaking. In our latest episode of About Time, we explore its design, its history and with the help of the newly revived Tank Must, check in with its current prospects. Along the way, we recognise its achievement of breaking out of the ranks of mere timekeepers to become something like a cultural icon as well – the Tank has attracted more influential wearers than just about any other watch in history (Messrs Truman Capote, Clark Gable, Muhammad Ali, Steve McQueen, Alain Delon, Andy Warhol, Duke Ellington… the list goes on and on). It also found itself about 50 years ahead of the curve in achieving widespread unisex appeal – Ms Jackie Kennedy, Princess Diana and Ms Ingrid Bergman all sported a Tank.

This is the second of our About Time videos to focus on Cartier – if you haven’t seen it already, our film on two Cartier dress watch options makes for a good companion piece. And while you’re there, why not discover our back catalogue – we have profiled the most important and most interesting watches from Vacheron Constantin, IWC SCHAFFHAUSEN, Panerai, Jaeger-LeCoultre and NOMOS Glashütte.