They were heartfelt and poignant. Most remarkably, they seemed spontaneous.

I’m talking about the makeshift memorials that suddenly appeared in American taverns, breweries and restaurants over the weekend to honor the 13 service members killed in action in Afghanistan on Thursday.

Most featured 13 glasses of beer on an otherwise empty table marked “Reserved.” Many listed the names of the fallen. Others had simple words of appreciation.

These tables were inspired, it seems, by the “Missing Man” table at many Armed Forces dinner events and they served as moving reminders of the Marines, soldier and sailor who were killed by a suicide bomber outside the Abbey Gate of the Kabul Airport as they tried to protect Americans and Afghans trying to flee that country.

No one seems to know who bought the first 13 beers and set them on a table marked “Reserved,” but by Sunday they were everywhere, from Cowboy Jack’s in Fargo, ND to First Line Brewing in Orchard Park,NY. From Klooz Brewz in Lebanon IN, to the Thirsty Horse Saloon in San Antonio. From Southern Craft in Bristol, Va to at least two local joints, O’Connor Brewing in Norfolk and New Realm in Virginia Beach.

A trip around Facebook found scores of these spontaneous tributes. Many included handwritten notes with the phrase,  “Til Valhalla,” a reference to Norse mythology and the legend of a grand hall where slain warriors go upon death on the battlefield.

In a military area like Tidewater, where countless families have known the gnawing dread of that knock on the door, an unknown number of watering holes reportedly paid tribute to the fallen warriors.

As I read the names of the deceased that were released by the Defense Department, I was struck by their youth. The oldest of the fallen was just 31. 

Five weren’t old enough to buy a beer.

Marine Corps Staff Sgt. Darin T. Hoover, 31, of Salt Lake City, Utah

Marine Corps Sgt. Johanny Rosariopichardo, 25, of Lawrence, Massachusetts

Marine Corps Sgt. Nicole L. Gee, 23, of Sacramento, California

Marine Corps Cpl. Hunter Lopez, 22, of Indio, California

Marine Corps Cpl. Daegan W. Page, 23, of Omaha, Nebraska

Marine Corps Cpl. Humberto A. Sanchez, 22, of Logansport, Indiana

Marine Corps Lance Cpl. David L. Espinoza, 20, of Rio Bravo, Texas

Marine Corps Lance Cpl. Jared M. Schmitz, 20, of St. Charles, Missouri

Marine Corps Lance Cpl. Rylee J. McCollum, 20, of Jackson, Wyoming

Marine Corps Lance Cpl. Dylan R. Merola, 20, of Rancho Cucamonga, California

Marine Corps Lance Cpl. Kareem M. Nikoui, 20, of Norco, California

Navy Corpsman Maxton W. Soviak, 22, of Berlin Heights, Ohio

Army Staff Sgt. Ryan C. Knauss, 23, of Corryton, Tennessee

Say their names.