COLUMBIA, S.C. — When Command Sgt. Maj. Teresa L. King was named the first female commandant of the Army’s elite drill sergeant school in 2009, proponents of gender equality in the military hailed the news as a watershed.

But it did not take long for the grumbling to start. Students who flunked out of the school complained that she set unfair standards. Some of her own instructors said she rigidly enforced old-fashioned rules. Traditionalists across the service asked: how could a woman with no experience in combat manage the Army’s only school for training the trainers who prepare recruits for war?

She says she tried to ignore the criticism, but her superiors did not. Last November, they suspended Sergeant Major King, forbidding contact with students or staff and opening an investigation into what they called the “toxic” environment at the school. As that review dragged on, she says she felt like a criminal: isolated, publicly humiliated and so despondent that friends worried that she might hurt herself.

Last week she decided to fight back, filing a complaint with the Army asserting that her male supervisors had mistreated her because she is a woman, and asking for a Congressional investigation. Four days later, the Army reinstated her, saying that the accusations against her — including that she had abused her power — could not be substantiated.