It’s a Wednesday, late June, and freshly shaved heads fill the pews of a church. The men wear camouflage uniforms, sleeves rolled above their elbows, pants tucked into their boots. The room is quiet, except for the new noises the recruits make: A commanding officer barks, and the men rise, their boots clack, their saluting right arms cut the air.

“Loyalty,” they shout.

These new South Korean military recruits arrived at this basic training facility five weeks earlier, pausing their lives for 21 months of mandatory service, the consequence of a constant threat of war on a divided peninsula. The recruits, many at least, simply hoped that normalcy would await them at the other end. But South Korean military officials describe the mandatory service as less an interruption than a conversion: Citizens become soldiers, and during five weeks of basic training, the recruits pitch tents, shoot guns, climb ropes, walk 18 miles through darkness and emerge as different people.

“You are reborn as soldiers,” a commanding officer told the recruits as they graduated from basic training.

South Korea’s compulsory military service remains controversial, with politicians debating its merits and dangers. In the meantime, conscription leads to something less hypothetical: a cycle in which men enter the service, adapt to lives of potential danger, then try to re-adapt to the lives they knew before.

Particularly in the past year, with 50 South Korean service members killed because of North Korean attacks, some analysts see further confrontation as inevitable. In that climate, South Korea’s mandatory service has become particularly harrowing.

“If you fight the enemy,” the commanding offer told the recruits, “you must win.”

A firsthand account

That same Wednesday, a 22-year-old who had just completed his military term took a test at Keimyung University — in polymer chemistry. He had spent the previous night at the library, where he often spends his nights, because he worries that the university president won’t approve of his grade-point average. Ahn Jae-geun gets more attention than most students here because he’s on a full scholarship. And he received his scholarship as a gesture of appreciation, one of the many unforeseen consequences of surviving a North Korean torpedo attack.

This is what happened, according to a report compiled after joint investigations by 73 experts from four nations: On March 26, 2010, at 9:22 p.m., a 290-foot warship called the Cheonan was ripped apart. A torpedo, rigged with 550 pounds of explosives, sent off a shock wave right underneath the vessel, and as the boat split, a 330-foot wall of water shot straight into the sky. There were 104 sailors on board — one guy taking a shower; one playing cellphone games; several in the gym — and 46 did not survive.

This is what happened, according to Ahn, sitting at a Starbucks not far from his university: The boat, on which Ahn had been stationed for almost a year, was patrolling waters near the maritime border. There was a loud bang, and the boat tilted almost 90 degrees. Everything went dark, and the contents of the boat — people, supplies, weapons, beds — came sliding toward one side, and some sailors were crushed under the weight of objects. Ahn, in the artillery chamber room, groped for a flashlight, then found his way to the top level of the boat, which was on its side. He held on like a kid on monkey bars.

He and 11 others waited like that for 50 minutes until rescue boats arrived.

“The 12 of us, we were the first to be rescued,” Ahn said. “The moonlight was really bright. And as we were pulled away, I could see the ship — our ship — cut in half, and people were on top of the ship, yelling and screaming. A couple of guys in my rescue boat started to cry. At that point, I knew people could be dead.”

Ahn had been a second-year university student before his service, and he’s now a third-year student. On Feb. 9, he met one-on-one with a top officer, who told him, “You’ve had a tough time, but well done,” and gave him a wristwatch. On Feb. 10, Ahn was discharged. On March 2, he resumed classes.

Some days, he feels bitter — abandoned and forgotten by the military. When zits form under his lip, he blames it on a lack of sleep and tries to hide them under the shadow of a Detroit Tigers cap. He wants to live twice as hard for the 46 who died, but he also tries not to think of them so often.

“One of my friends had 40 days left until he was discharged,” Ahn said. “I was really close to him. About 20 minutes before the attack happened, he came to me and was annoying me, asking for a snack or something to eat. He was kind of bored. I told him to go away, and he went in the TV room. I keep thinking if I had told him to stay with me, he maybe could have been saved.”

Generations of service

At the Wednesday graduation ceremony in June, marking the end of basic service and the start of a formal assignment, the church was filled not just by the recruits, but also by their parents and grandparents and siblings — a brigade armed with day-packs and camera bags and coolers of picnic food. The relatives hadn’t seen the recruits in five weeks, and some parents said they felt nervous, or proud, or just a little surprised. And when the 900 recruits boomed, “Loyalty!” the family members let out a gasp, then applauded.

After the ceremony, Jeong Woo-jae, 21, met up with his family — his mother, who had spent days preparing food, and his father, who had served what was then a mandatory 30 months, and his grandfather, who had fought in the Korean War. As the family walked toward lunch, Jeong held his pet Maltese. Jeong’s father clasped the recruit’s arm just above his elbow.

At the picnic spot, about 500 yards from the church, the mother spread out a feast of bulgogi, rice, seaweed and doughnuts. She told Jeong, “You look tired.” The grandfather stuffed a rice ball in Jeong’s mouth.

As they ate, Jeong said little. In the coming days, his parents would receive a text message informing them where their son would be stationed.

As lunch was winding down, Jeong’s grandfather took out a notepad and a pen. He drew a map of the Korean Peninsula, etching every angle and inlet, which he knew because he had once marched from the south to the north. With a few violent strokes and underlines with his pen, he wrote a date at the top of the map — June 25, 1950, 4 a.m. — and began telling stories of the war. He pointed to a northern part of the map: Here is where the Chinese had surrounded him. He pointed to his right hip: Here is where the bullet pierced him. He pointed back to the map: Here is where he spent weeks in a hospital.

And, eventually, he even got back to fighting. When his three sons joined the military, Jeong Jeong-keun, now 78, told them, “Be ready to die for your country,” though they all came out of it fine. And now Jeong lowers his voice and looks up from the notepad.

“It’s the same,” he says, “for my grandson.”

Special correspondent Yoonjung Seo contributed to this report.