Late at night while going through preliminary training for the Army’s Ranger School, Maj. Lisa Jaster questioned one of the male soldiers in her class: Why was he so opposed to women being there?

The ensuing conversation at Fort Benning, Ga., took more than an hour, and cut into an already short night of sleep, she recalled in a question-and-answer interview on Facebook with fellow alumnae of the U.S. Military Academy at West Point, N.Y. She brought up the issue while observing that both male Ranger instructors and students were struggling to adapt to the idea the service was opening the legendarily difficult school to women for the first time, she said.

“I asked Johnson, ‘After three days of training with us, can you explain to me why you still think women don’t belong?” she recalled in the Facebook post, since taken down. “I added, I am completely okay if you don’t think women should be here, I just want an educated, civilized discussion that considers the women you have been training with over the past 3 days.”

On Monday, the Army announced that Jaster, 37, has become the third woman to ever complete the Ranger School course. She will join Capt. Kristen Griest, 26, and 1st Lt. Shaye Haver, 25, who earned the Ranger tab on Aug. 21. Jaster will join 87 men in receiving the coveted decoration in a ceremony at Fort Benning on Friday. At graduation, Jaster will have spent 180 days in the course — far longer than the minimum 61 it takes, but within the realm of the possible for male or female students.

The three female soldiers are the only women to pass Ranger School among 19 who attempted the course beginning in April after the Army opened it to women for the first time. It did so as part of the military’s ongoing research into how it will integrate women into new combat roles in the future. The move followed a landmark January 2013 decision by then-Defense Secretary Leon Panetta, who opened all jobs to women, but gave the services until this fall to research how to integrate and make recommendations about each position that was closed.

Like most of their male counterparts, Griest and Haver are relatively early into their careers. They made it through Ranger School while relatively young, and have rejoined their units since being lauded as trailblazers this summer.

Jaster, on the other hand, has had an even more unconventional path. Like Griest and Haver, she is a part of the first generation of women who will be able to earn the Ranger tab. But she’s also a higher-ranking officer in the Army Reserve, a mother of two children, and an engineer who temporarily left a position with the Shell Oil Company in Houston to tackle Ranger School.

“I just think it’s phenomenal for her to do this at that age,” said Terron Sims II, a former Army captain who graduated from West Point with Jaster in 2000. “Forget gender. Her willingness to sacrifice at that age is just phenomenal and speaks a lot about her.”

An administrator for the West Point class of 2000 Facebook page said Jaster’s fellow classmates look forward to toasting her this weekend, as she receives the Ranger tab in Georgia as they gather a day later for their 15th reunion.

Andrew Exum, a deputy assistant secretary of defense who previously served as a Ranger, also shared amazement in a tweet on Sunday, after The Washington Post first reported that it was likely Jaster would graduate.

“I can’t believe a 37-year-old graduate from Ranger School,” his tweet said. “I’m 37. I went when I was 22. 37 is oooooold.”

Jaster, whose maiden name is Peplinski, joined the Army in 2000 and served about seven years on active duty. She was initially assigned to Fort Stewart in eastern Georgia with the 92nd Engineer Battalion, and deployed in support of the wars in Iraq and Afghanistan in her first four years, she said in the interview posted to the West Point page in May.

Jaster, who could not be reached for comment Monday, was then reassigned to Fort Leonard Wood, Mo., for school, where she met her husband, Marine Lt. Col. Allan Jaster, she said. She left active-duty in 2007 and started a family and civilian career with Shell, but returned to the Army as a reservist in 2014, according to a LinkedIn profile listed for her.

The desire to remain physically fit apparently never left her while she was a civilian, however. She is listed as a participant in weightlifting competitions in Texas, and said in an online profile that she took up CrossFit workouts after the birth of her second child in 2012.

Jaster said in the interview posted on Facebook that the senior enlisted soldier in her reserve unit suggested she attempt Ranger School after the Army announced it was opening the course to women.

“A lot of doors can open for women if we go about it the right way,” she said. “The right way includes being professional, thick skinned, and ensuring that we minimize any special treatment. I know that I am physically fit. I am mentally tough. I know that I have all the ingredients to be successful. I volunteered because I want to make sure the standards do remain high and that the women coming out at the far end of Ranger School will be respected for their accomplishments rather than being judged for making things easier.”

At Shell, Jaster has worked on the management of brownfields — sites tainted with pollution — and managed contracts and construction, according to her LinkedIn profile. Jaster’s manager, Hans Hofland, congratulated her in a statement released Monday by company officials.

“We are very proud of Lisa and her ability to achieve such an extremely demanding goal,” Hofland said. “Her ability to do well under pressure is exemplified in this achievement and it comes as no surprise to us that she was successful.”

Jaster’s husband declined to comment on Monday, citing a desire to connect with his wife before speaking to media. His wife has credited him with being a huge source of support on social media, as well as a workout partner in the gym.

“My husband goes on weight vest runs with me,” she said in the earlier interview. “My kids are actively involved in my training either as added weight for rucks or chin-ups or bike rides. Everyone in my family competes in something from Races to Brazilian Jiu Jitsu and more. We are a family that ‘plays together.'”

Jaster was able to complete Ranger School despite being held back in each of its phases through what is known as “recycling,” a common practice in which students are allowed to repeat a portion of the course, but only if they show promise and fell short in a specific aspect of training.

Griest, Haver and Jaster all moved on from the first phase of training at Fort Benning to the second phase in the mountains of northern Georgia after recycling twice and being allowed to start over from the beginning a third time.

Griest and Haver completed the Mountain Phase on their first try, but Jaster recycled once there, too. She advanced to the third phase in the swamps on and near Eglin Air Force Base, Fla., in August, but was held back once there, as well.

Army officials have said that it is uncommon for students to be recycled that much, but that it occurs on occasion.