In November 2016, Navy Senior Chief Petty Officer Scott Dayton became the first member of the United States military to die in the continuing conflict in Syria. Chief Dayton was killed by an improvised bomb in the northern part of the country, during a raid against the Islamic State. He was an explosive ordnance disposal technician, a member of the elite bomb squad, as was I, and everyone called him Scotty. He left behind a wife and two children. He was 42 years old.

Forty-two. Scotty served 24 years, most of them at war, and he did it by choice. In the days after his death, I spoke to a number of his friends and fellow E.O.D. technicians to ask why he made that choice, to go back after already completing at least five tours in Iraq and the Persian Gulf. They all gave basically the same answer, and if you are as war-weary as I am, you may be surprised to hear it: Scotty wanted to go to Syria, they told me, to finish the long fight, to do his part until the job was done.

The longest conflict in American history — from Afghanistan to Iraq, to high-value target missions throughout Africa and the Middle East — has resulted in the nation’s first sustained use of the all-volunteer military, wounding and killing more and more service members who resemble Scotty: parents, spouses, career men and women. When compared with casualties of the Vietnam War, the average age of our dead in this conflict, and the proportion who are married, have both risen 20 percent. And that trend is accelerating as the burden of the fight shifts more and more to older, highly trained counterterrorism forces. As The Times reported recently, of the 18 service members lost in combat since 2016, 12 were Special Operations troops like Scotty.

Our country has created a self-selected and battle-hardened cohort of frequent fliers, one that is almost entirely separate from mainstream civilian culture, because service in the Forever War, as many of us call it, isn’t so much about going as returning. According to data provided by the Center for a New American Security, of the 2.7 million veterans of Iraq and Afghanistan, half have done multiple tours. More telling, 223,000 have gone at least four times, and 51,000 have done six or more deployments.