The U.S. Army announced Friday that the general who pleaded guilty to adultery and other charges in March will be stripped two ranks before his retirement, slashing his future benefits.

Brig. Gen. Jeffery Sinclair, 51, will be retired as a lieutenant colonel, an Army statement said.

Sinclair pleaded guilty earlier this year during a court-martial where he faced criminal charges of adultery, maltreatment of a subordinate, engaging in improper relations and other charges.

"Sinclair displayed a pattern of inappropriate and at times illegal behavior both while serving as a brigadier general and a colonel.  I therefore decided there was sufficient evidence and cause to deny him those benefits," John McHugh, the secretary of the Army, said in the statement.

He is reportedly the first general in a decade who had his rank dropped two grades prior to retirement.

Sinclair had a three-year affair with a female captain who accused him of twice forcing her to perform oral sex on him. The former deputy commander of the 82nd Airborne Division was originally brought up on sexual assault charges punishable by life in prison. Sinclair was spared prison and fined $20,000.

He was believed to be the highest-ranking U.S. military officer ever court-martialed on such charges. And, the Army said this is the first time in a decade that the service has reduced a retiring general officer by two ranks.

"Gen. Sinclair has consistently taken responsibility for his mistakes and agreed to a reduction in retirement benefits," his lawyer, Richard Scheff, said in an emailed statement. "He is a highly decorated war hero who made great sacrifices for his country, and it's right that he be permitted to retire honorably."

Fox News' Edmund DeMarche and The Associated Press contributed to this report