Jacob Eleazer, a 28-year-old TAC (Teach, Assess, Council) officer, learned he was up for promotion this December. For seven years, he’d been an exemplary soldier, rising to the rank of first lieutenant, and now on his way to captain. But there was a problem. Within the confines of his military training center, in western Kentucky, Eleazer still went by his birth name, which was female.

Outside his Army base, Eleazer lived as a man, one of 15,450 military personnel who consider themselves transgender, according to a recently released study, but don’t dare come out to their fellow soldiers and risk jeopardizing their careers.

“My colleagues just assumed I was a really butch lesbian,” says Eleazer, who has broad shoulders, close-cropped hair and a jutting chin.

Jacob Eleazer: "My colleagues assumed I was a really butch lesbian."

Like Chelsea Manning, the former Army private who gave classified documents to WikiLeaks when she was known as Bradley Manning, Eleazer hadn’t identified with his gender since puberty. Yet he believed that undergoing any kind of anatomical change was unrealistic—too many complications—and so for years he lived as a lesbian. But in 2011 he decided he couldn’t abide the dissonance any longer. He soon came out to his friends and family, who were supportive, and for the last two years, he has lived as Jacob. But he only recently resolved to surgically modify his gender.

Not all transgender men and women in the military, however, wish to make such a transition. So as long as they are quiet, their secret is safe, but any major medical procedure must be reported to the military. And just when Eleazer learned he was up for a promotion, he also learned that a doctor could remove his breasts. If he passed on the operation, another opening in the doctor’s schedule might not present itself for a while.

Eleazer understood the risks.

“The hardest thing,” he says, “was deciding whether to transition or stay in the military. I identify very much as a soldier.”

For decades, transgender men and women have been barred from serving in the military. The rule is rooted in an archaic theory that equated being transgender with having a mental disorder. Four years after Congress repealed the “don’t ask, don’t tell” law, activists have been agitating for change, and point to other nations, like Israel and England, which allow transgender military personnel. Last week, an independent commission, led by a former U.S. surgeon general, released a study confirming what psychiatric doctors have known for years: “There is no compelling medical reason for the ban,” as the report states, and it has no legitimate basis. The commission called on President Obama to overturn it immediately.

Whether or not the ban is ultimately overturned, Eleazer’s fate is now precarious.

“I’ve been dreading the process for a while,” he says. “Being in the service has been a dream.”

Indeed, Eleazer’s view of the Army is almost sentimental. “I always wanted to be part of something larger than myself,” he says. “I feel I have a debt to pay. And watching these young soldiers walk in, all terrified? I get to see them grow into the future leaders of the military, and that’s incredibly meaningful to me.”

Eleazer is one of more than 15,000 military personnel who consider themselves transgender.

Still, there was not really a choice for Eleazer. “You get sick of trying to hide,” he says. “And this was about valuing myself, needing to feel comfortable in my body. I didn’t want to lead a double life anymore.”

He elected to have the surgery, and in January notified his commander, who has the distinction of being the first female TAC officer at the installation. She had been a mentor to Eleazer, who was the second.

“I was worried she’d feel I’d been lying to her,” he says. “That she’d feel betrayed.”

But the commander was unperturbed, even encouraging, and opted to promote Eleazer anyway. He was still concerned about his other colleagues, the two officers with whom he drilled candidates. They were “standard conservative masculine dudes,” and for a long time he’d been evasive with them about his personal life. But they were unbothered, too. One of them even said, not unkindly, “Well, that makes sense.”

Eleazer's lawyer aims to convince the military that he isn't mentally ill.

But the decision about Eleazer’s fate does not rest with his colleagues or commander. It is now up to a panel of field-grade officers who will soon call him to plead his case. He will appear before them wearing his best uniform, though he is unsure whether to wear a man’s or woman’s. Eleazer’s lawyer will present evidence and call witnesses to prove only one point: that he is not mentally ill.

There’s little chance that the panel will allow him to continue serving. Instead, he’ll likely be discharged, which poses yet another obstacle: Anything less than an “honorable” distinction will impede the rest of Eleazer’s career. Without such a grade, it would be all but impossible to obtain a federal or state job, which is part of his plans for the future.

“Who’s going to have me if the military claims I can’t perform?” he says.

Meanwhile, he will continue to perform his duty for as long as his superiors allow him. He says that in mid-April, during the next session of drill, he’ll explain his situation to his young candidates, who may struggle to process the information. But Eleazer is not especially concerned about the conversation.

“I don’t ask their opinions about things,” he says. “I’ll probably take my hat off and have a talk about it. Then I’ll put it back on, and it will be business as usual.”