In recent weeks, a widening scandal has erupted over secret all-male groups of Marines and veterans that posted nude photos of female Marines online without their knowledge and consent, and often included names, ranks and where the women were stationed. A new article, the third I’ve done on the unfolding scandal, reports on young Marine veterans who have taken up the fight against the harassment online, saying the Marine Corps leadership is not sure how to tackle the problem. But as is often true, there are interesting side stories that don’t make it into the main report. Such is the case with the inspiration for some of the anti-harrassment efforts: Saint Mattis.

In a photo with today’s story, a former Marine captain named Shawn Wylde, who spent $10,000 taking out targeted Facebook ads asking Marines to help him reveal the identities of those sharing photos, leans on his desk. A poster over his shoulder features Defense Secretary Jim Mattis dressed like a medieval saint, complete with halo, and gripping a knife and a grenade. Underneath it reads: Saint Mattis of Quantico, patron saint of Chaos.

The image, created by Mr. Wylde, is so wildly popular that it now hangs unofficially in Marine bases around the world. Mr. Wylde, who owns an online, military-themed T-shirt company, has also sold more than 100,000 shirts featuring the tough-talking Mr. Mattis, who has become a cult figure among Marines.

That a defense secretary could have such resonance in the rank-and-file shows that Mr. Mattis is no ordinary secretary. While most recent picks to lead the Pentagon have been policy wonks with Ivy League degrees, Mr. Mattis is a combat-hardened Marine and that most dubious of modern achievements, internet meme.