The changes at Womack, they said, were due both to the patient deaths and to problems with surgical-infection control identified in March by the Joint Commission, an independent body that accredits hospitals. In a statement, the Army said that “senior Army medical leaders have lost trust and confidence” in Womack’s commander, Col. Steven J. Brewster, and had replaced him with Col. Ronald T. Stephens, another doctor.

New acting deputies were also named to head clinical services, nursing and administration while investigations into the deaths continue.

Womack is one of 41 domestic inpatient hospitals run by the Defense Department, serving active-duty service members and their families, as well as long-serving retirees and their families. The separate system run by the Department of Veterans Affairs principally cares for those who left the military after less than 20 years. Federal investigators are examining allegations that records were altered at more than two dozen veterans hospitals to disguise a backlog of patients awaiting treatment.

The first of the two recent fatalities at Womack involved Racheal Marie Rice, a 29-year-old mother of three who underwent a routine tubal ligation on May 16 and died the next morning, according to hospital staff members. The procedure is considered low risk for complications and death. Within three hours of surgery, Mrs. Rice, the wife of an active-duty soldier, returned to the emergency room, feeling ill.

Patients who return that soon after surgery are supposed to be placed on a triage list and seen quickly. But Mrs. Rice waited for about two hours without seeing a doctor, then left to breast-feed her baby, who is about 6 months old, according to people familiar with the case. By the next morning, she was close to death. An ambulance took her from her home back to Womack, where she died.