Originally designed as outerwear that could camouflage and be worn comfortably over military uniforms, trenchcoats are now sought out as much for making a fashion statement as they are for function. With options available in various colors, lengths and designs, how does one choose?

Because the coats are typically worn in cooler and rainy weather, a roomier fit will better accommodate the layers people may have on underneath, according to Chenelle Delgadillo, a stylist to celebrities including singers Olivia Rodrigo and Rosalía.

Shorter trenches that hit between the hip bone and the knee, Delgadillo said, tend to be the least flattering on the body. Styles that hit a few inches below the knee, she added, are generally easier to wear with pants and skirts of all lengths, making them more versatile than floor-sweeping versions.

Longer trenches, though, are considered by some to be more stylish. Those with a vent down the back “allow you to sit comfortably,” said Sebastian Szafarczyk, the owner of Check It, a boutique in London that specializes in vintage trenchcoats and other items from British label Burberry.

Burberry and another label founded in London, Aquascutum, are widely considered to be the inventors of the trenchcoat. During World War I, each brand created versions worn by the British military.

More than a century later, Burberry remains a standard-bearer of trenches; it now offers more than a dozen styles that start at about $1,550.

By World War II, trenchcoats had been embraced by American soldiers, who were outfitted in versions made by the company that eventually became known as London Fog.

After the war, soldiers who continued to wear trenches in daily life helped popularize them with the masses, Szafarczyk said. So did the coat’s associations with actors like Alain Delon and Humphrey Bogart and fictional characters like Inspector Gadget and Carmen Sandiego.

Trenchcoats’ postwar ubiquity was a reason they were embraced by detectives both real and imaginary, said Darrin Giglio, a chief investigator at North American Investigations, a company in New York offering surveillance and private-investigation services. “Back in the day it would help you blend in because it was a common jacket for men to wear,” he said.

But nowadays, Giglio added, surveillance professionals like himself tend to avoid them. “It would almost be cliché if I wore one today,” Giglio said. “I might not be taken seriously.”