A white quad-copter drone saddled with a camera buzzed above us at Brooklyn's Floyd Bennett Field while a uniformed soldier warbled her way through the national anthem, discordant but in harmony just the same. As she finished, the microphone was passed to Sergeant Major Mike Lillie of the United States Marine Corps.

"We're gathered here today," he yelled, "to pay homage to the unique civilian-military relationship this country has had for the past two hundred years." The crowd, a few hundred people strong and uniformly attired in athletic gear but not uniformly athletic, nodded, and clapped. There were a few hoots, and some hollers. The drone buzzed as enthusiastically as it could.

Lillie, in his dress uniform, spent the next ten minutes or so shouting historically questionable things at us about the Revolutionary War. "America was founded here," he said. "We signed the paperwork in another state, but the battle was here. It got raw; it got real."

It was in Brooklyn that we threw off the cold blanket of tyranny and took up the mantle of liberty, Lillie said, suddenly rattling off words in an un-prefaced list: Battle of Brooklyn; 9/11; America.

"New Yorkers again today rise to meet another challenge," the sergeant major said, striding back and forth between rows of Merchant Marine Academy midshipmen standing at attention. "This obstacle course." He finished, and the DJ played, as if on cue, Creed's "My Sacrifice." The drone dropped down to get some shots of people's smiling faces, buzzing in as close as it could.

We were here, two reluctant friends and I, on this bright Saturday morning in September, for the Civilian Military Combine's 2014 NYC Urban Assault, a military-inspired, CrossFit-inflected obstacle race. CMC was founded by three former Wall Streeters who discovered CrossFit shortly before participating in the first-ever Tough Mudder race in 2010.

"In the parking lot after, having a beer, chest bumping, we saw the vision," CEO and co-founder Keith Gornish told me. "We needed to bring together functional fitness—and obstacle racing." Gornish said that since 9/11 he had been looking for a way to support the military, to do his part as a civilian: CMC is partnered with organizations like the Travis Manion Foundation and One Team One Fight, which raise money to support veterans and veterans' families. Its merchandising and marketing materials are also so closely patterned after the U.S. Army's that I thought, when I first learned of CMC's existence, that the two were affiliated.

"We can make patriotism fun. The military can be very fun," Gornish said. On the day of the combine, Marine recruiters set up across from a tent full of massage tables. "There are some events that are, you know, inspired by the Navy SEALs. 'This is what it's like to be a Navy SEAL.' We're… getting that? But, you know. We have a DJ."

"We want you to demonstrate your patriotism," he said, "through athleticism."

Sergeant Major Lillie had been speaking to us from The Pit, where the first and most intense part of race takes place. Participants complete super-sets of three exercises prescribed by one of four divisions: Alpha, Bravo, Charlie, or Delta. You have five minutes to complete the set as many times as you can. Then, you head out onto the tarmac of Floyd Bennett Field, a former municipal airport and naval air station at the very southeast tip of Brooklyn. Running paths criss-cross the overgrown woods between the runways; both the paths and runways were spotted with obstacles for race participants to conquer—hay-bale stacks, high walls, low walls, a 50-lb sandbag carry, A-frames with ropes, A-frames without ropes, monkey bars, low crawls beneath barbed wire. The course, billed as "The Ultimate Test of Strength, Endurance, and Agility," was a bit over four miles long.

About eighty percent of Civilian Military Combine participants run the race in teams—CMC encourages this. The idea is that if you're a part of a team, you can help your teammates either physically or rhetorically through obstacles that they are struggling with. Kinda like a mini army. This is not untrue, but it is also true that in order to run this race you have to pay between $94 and $141, depending on how far out in advance you sign up, and that convincing people that they need to get their friends to do this thing with them also means more ticket sales. "CMC does not disclose any financials," a spokesperson told me, nor could they tell me exactly how many people ran in the race. When I checked the CMC scoreboard last week, however, there were 1,774 names listed as having finished the 2014 NYC Urban Assault, generating somewhere between $110,356 and $250,134 in revenue. CMC will host five events in 2014 altogether.

Every few minutes the drone's cartoon-swarm-of-bees buzz would emerge from between the thumping tunes—"CMC is really like a fitness concert," Gornish had said—playing over the PA system as the quad-copter swooped back and forth over the crowd gathered around The Pit. Outside, spectators, many of them Combiners waiting their turn, watched and clapped and made comments under their breath about other participants' form. "That's not a real burpee," someone muttered.

"There are a lot of eyeballs on you when you're in The Pit," Gornish had told me. "People care about what they look like. People have, like, the shades on—they look so good. The girls are all done up. This is like a fitness fashion show. Which is great, because our sponsors and brands love it."

Eyes widened and then rolled as one particularly breathtaking specimen of humanity, standing well over six feet tall, glistening with sweat in the late morning sun and having had someone draw Superman's insignia across his chest in Sharpie, muscled his way through his AMRAP sets with quickly deteriorating form. Many men went shirtless, so as better to display their pecs, six-packs, and tattoo sleeves. (Wouldn't you?) One wore a GoPro strapped to his chest; another wore one strapped to his bald head. I thought I looked pretty good, myself—very sporty in expensive athletic tights, shorts, and a basketball pinnie.

The vast majority of every group who wasn't mine appeared to composed of members of the same CrossFit gyms. Seemingly all of the Combiners (1,774 people, according to the results page) wore uniforms: some homemade, some printed, usually with the name of their home gym, but sometimes with something more creative: Cubicle Warriors, for example, or Children of the Dungeon.

My team's heat entered The Pit around noon, well after our scheduled 10:37 start time. I had not brought sunscreen, and was already burned. We jogged out into The Pit, each to our individual station and introduced ourselves to the trainers assigned to watch our form (allegedly) and to count how many reps we completed. My trainer took my name down and what division I was participating in: Alpha, which called for sets of five burpees, seven 20" box-jumps, and nine sit-ups. He shouted tips into my ear about each of the movements—make sure your chest touches the ground with the burpees; make sure your hips come all the way up and through with the box jump; make sure your shoulder blades touch the ground and you come all the way up with the sit-ups—before the countdown began.

I knew that The Pit was going to be the most difficult part of the day for me. I'm active enough: I lift three times a week, play pick-up soccer in Prospect Park most Sundays, and bike a lot. But I didn't specifically prepare, or train, for this kind of high-intensity work-out. I wasn't worried about it, but I wasn't expecting to crush it, either. What's more, I don't often find myself in a place where I am less fit than the average person in the immediate vicinity. But standing in The Pit, looking around at the other Combiners in our heat and out at the crowd on the bleachers around us, I suddenly became very aware, in my sleeveless shirt, of my shoulder muscles, or lack thereof, and the definition of my pecs, or lack thereof. I was glad I had worn tights, the dark fabric doing something, maybe, to disguise my perennially skinny calves. You look like a child, I thought. You're never going to have a six-pack, I thought. You're not strong, or tough, or athletic, and it's hilarious that you ever thought you might be, I thought.

Anyway, the countdown hit zero, and five minutes later, I had completed 81 reps of burpees, box jumps, and sit-ups—3.85 sets altogether. I felt fine about it. A respectable enough result. One of my teammates had completed far more reps than I had, and I was impressed, but he also looked like death, whereas I felt pretty energized. So that was fine.

We filed out of The Pit and towards the starting line, gulping down water and something sweet with electrolytes. Another countdown passed, and we ran out onto the airfield as the heat behind us began their own AMRAP workout. The first few obstacles came maybe a quarter-mile out from the start, well away from the noise of The Pit: hay bales, stacked atop one another. We clambered over and kept running, turning from one strip of tarmac to another. In the distance, through the treeline, we could see the water of Jamaica Bay. We clambered over the next obstacle—a wall, maybe seven or eight feet high—and kept running.

The obstacles changed as the course went on, but the majority took this form: here is a relatively high thing—get over it. Or walk around! It's fine. Nobody's looking, and nobody cares, except maybe your teammates. About half of the course was set in the woods, on a path well-groomed enough that you'd have to do something really strange to roll your ankle. In the last mile, the obstacles became a little more involved—this was where we had to carry the 50-lb sandbag, for example, and traverse a climbing wall, and run through some mud. Also we got to run/jump over a line of parked cars, which was fun, past an armored military truck surrounded by machine guns, which was weird and scary.

The penultimate challenge was the most difficult—a second low crawl, longer than the first, through dirt and sand, beneath barbed wire. Some Combiners, rather than facing forward and crawling on their stomachs, rolled sideways the length of the obstacle (maybe a hundred yards). I did not do this, choosing instead to crawl beneath the wire, risking a scratch on my back, because I thought the rolling thing looked rather silly. I ended up getting sand kicked in my face.

The finish line came on the other side of a glorified jungle-gym, all rope ladders and firemans' poles. It was, like most of the race, impressive-looking, but not particularly challenging. Crossing the finish line, we ended back where we had begun, as many races do: in the spectacle, in a crowd of people browsing merchandise from brands with names like Progenex and Hylete and Rage Fitness and Wreckbag that identify them as having been subsumed into the overarching lifestyle brand that is CrossFit, upon which things like the Civilian Military Combine is dependant. "The event is one piece of an overall lifestyle. We want people to embrace wearing the gear. And meet a lot of fun, inspiring people," Gornish told me. "We want to be the one event, the one brand, that brings everybody together."

The Civilian Military Combine has an ethos. "We are the men and women who rise to train before the sun comes up. Our hearts make their own fire," it begins. "We hear the voices chanting "slow" and "stop," but choose not to listen. Our greatness is earned in the face of great challenge." This is—not to put too fine a point on it—more than a little bit silly. The fact of the matter is that the race, or at least this iteration of it, was not an especially great challenge. I broke a sweat, but pick-up soccer has left me more sore and beat up than CMC did. (It may be worth noting that after the race I inhaled approximately two thousand calories worth of Shake Shack—burger; fries; soda; ice cream—before watching seven hours of The Walking Dead, but it would also then be worth noting many Saturdays previous were not dissimilar.)

When we finished, we were given a t-shirt, and a draw-string bag, and a dog-tag, on the back of which was printed the Ethos's final stanza. "Our greatness is earned in the face of great challenge. I will compete to honor my heroes. I will persevere for my team. I will finish because I started," the back of the dog-tag reads. "I am CMC." But on the course, and even in The Pit, there was no CMC, no brands at all, no Sergeant Major Mike Lillie, no anxiety about jingoistic nationalism—just sunburn and stuff to climb over. At bottom, it's just LARP-ing for jocks, playing Army for grown-ups.

"We look like we're 12," I said when my dad, who drove up from New Jersey to watch and to cheer us on and buy us Gatorade, showed us the photograph he took of the three of us finishing, holding hands, because we had said at the start that that was how we would finish. "You should look 12," he said. "It's fun!" He wasn't exactly wrong.

Brendan O'Connor is a freelance journalist in New York City.

[Photos courtesy of Civilian Military Combine, top photo illustration by Tara Jacoby]