The Marine got married in February, on Valentine’s Day, before being sent overseas on his first deployment in April. The newlyweds were expecting their first child.

Then, two weeks ago, 20-year-old Lance Cpl. Rylee McCollum was transferred to Afghanistan, McCollum’s sister, Roice McCollum, said in an interview.

The knock came sometime after 3 a.m. Friday at McCollum’s father’s home in Bondurant, Wyo.: His son, the two Marines at his door told him, was among 13 U.S. service members killed in Thursday’s attack outside the Kabul airport.

McCollum was working the security perimeter at the Abbey Gate of Hamid Karzai International Airport when a suicide bomber detonated an explosives belt, killing at least 170 people in addition to the 13 U.S. service members. The death toll is expected to rise.

McCollum is among the most recent U.S. troops to die in a war that has lasted as long as he had lived, and the most recent to leave a child without a father — in his case three weeks before the baby is due.

Roice McCollum said her family and McCollum’s wife, Jiennah, who lives in San Diego, have been devastated, but “we knew he was where he wanted to be: serving his country. And that brings a little bit of peace and comfort.”

Rylee McCollum, just a baby on 9/11, grew up in Jackson, Wyo., and wanted to join the armed forces since he was as young as 2, his sister said.

“He signed up the day he turned 18,” Roice McCollum said. “That was his plan his whole life.”

Their father, James McCollum, also had hoped to join the military, Roice McCollum said, but medical issues prevented that career. Her father, she said, “always passed that passion on, and Rylee just loved it. He wanted to be so patriotic.”

Rylee McCollum attended Jackson Hole High School and Summit Innovations School in Jackson, and he was a decorated wrestler.

His longtime coach Ben Arlotta said he started teaching McCollum wrestling moves when he was 5 years old. They drove to wrestling tournaments across the country — Idaho, Nebraska, Iowa and elsewhere. McCollum was 9, Arlotta said, when he first told him that he wanted to be a Marine when he grew up, while driving home from a tournament. To Arlotta, it made sense.

“The kid was cast-iron tough,” Arlotta said in an interview. “It was really more about his resolve. He was stubborn as all get out. He was never going to do anything he didn’t want to do himself. He aimed high in everything, and worked his tail off for everything he ever had.”

He didn’t just inspire his teammates, Arlotta said, but the adults too. Before one state tournament when McCollum was in middle school, Arlotta made a deal with him: If he could lose 30 pounds to make weight, Arlotta would quit chewing tobacco.

Somehow, Arlotta said, the athlete managed to do it — and the coach hasn’t chewed tobacco since.

The story encapsulated his unrivaled willpower, Arlotta said. “It was exactly who he was.”

“He was always much bigger in character and in spirit than he was physically,” Arlotta said. “He was always much, much bigger. I mean, quite frankly, I think he was much bigger than all of us.”

When it came time for McCollum to join the Marines, Roice McCollum said her brother insisted on the infantry. His recruiter tried to talk him out of it, Arlotta said — he was always intelligent, and there were other ways he could serve. But McCollum had his heart set on it, his coach and sister said.

After graduating from high school, McCollum went to boot camp last year in San Diego, where he met the woman who would become his wife, Roice McCollum said. He dreamed of one day becoming an American history teacher and a wrestling coach, passing down the same passions he picked up as a kid in Jackson.

Before he left for his first deployment in Jordan, Arlotta gave him a knife he made, protection in case he ever needed it.

“I lost a brother today,” he said Friday. “This whole family lost a family member today. He was a son of Jackson. He was a son of Wyoming. He was a son of the United States. There’s a lot of us hurting pretty good right now.”

Officials from his home state echoed that loss Friday.

“As Rylee’s dad once said, he was ‘full-blooded red, white and blue,’” Sen. John Barrasso (R-Wyo.), said in a statement. “Rylee’s sacrifice will never be forgotten. We will always be grateful for his service.”

Rep. Liz Cheney (R-Wyo.) agreed.

“His willingness to put himself in harm’s way to keep our country safe and defend our freedom represents a level of selflessness and heroism that embodies the best of America,” she said in a statement.

Gov. Mark Gordon (R) said flags would remain lowered until Monday.

Roice McCollum said as she watched from afar as the chaos unfolded at the airport in the days after the fall of Kabul, she started to get a bad feeling that something terrible could happen, but she had no way of communicating with McCollum. The family had not been able to speak to him since he had been in Afghanistan after his phone broke in Jordan, she said. The last time she spoke to him was a month ago — nothing special, she said, a quick catch-up.

Weeks were left in his tour. His family expected that he would be home just in time to meet his new son or daughter — the newlyweds wanted the baby’s gender to be a surprise.