A 24-year-old lieutenant made history when she became the first and only woman in the Marine Corps to lead an infantry platoon.

Lt. Marina A. Hierl’s historic achievement came last September, when she graduated from the Marine Corps’ Infantry Officer Course at Quantico, Va., the New York Times reported. Hierl was the second woman to complete the grueling 13-week course.

The lieutenant, however, is the only woman to lead a platoon of about 35 men.

“I wanted to do something important with my life,” Hierl told the New York Times. “I wanted to be part of a group of people that would be willing to die for each other.”

Hierl, from Bethlehem, Pa., said her interest in joining the Marines began in high school when she met with a recruiter. She said joining the Marines “sounded good,” but the recruiter advised the then-high school student to finish college before propelling her career toward becoming an officer.

Hierl went on to attend the University of Southern California. She recalled in 2013 hearing then-defense secretary Leon Panetta announce the ban on women in combat roles was finally lifted — a moment that became a turning point for her.

“I wanted to lead a platoon,” she said. “I didn’t think there was anything better in the Marine Corps I could do.”

The U.S. military remains dominated by men, with women only making up 15 percent of the active-duty troops. Only 15,885 of the 184,473 active-duty Marines are women, the New York Times reported.

Monday also marked the 100th anniversary of women in the Marine Corps.