Peake served for four years as the United States Army Surgeon General. He also served as commander of several Army medical units. Key assignments include Commander, U.S. Army Medical Department Center and School and Installation Commander, Fort Sam Houston, Texas; Deputy Commander, U.S. Army Medical Command, Fort Sam Houston, Texas; Commanding General, Madigan Army Medical Center/Northwest Health Service Support Activity, Tacoma, Washington; Commanding General, 44th Medical Brigade/Corps Surgeon, XVIII Airborne Corps, Fort Bragg, North Carolina; Deputy Director, Professional Services/Chief, Consultant, Office of the Surgeon General, Falls Church, Virginia; Commander, 18th Medical Command and 121st Evacuation Hospital/Command Surgeon, Seoul, Korea; Deputy Commander for Clinical Services, Tripler Army Medical Center, Honolulu, Hawaii; Assistant Chief, Cardiothoracic Surgery, Brooke Army Medical Center, Fort Sam Houston, Texas; Staff General Surgeon/Chief, General Surgery Clinic, DeWitt Army Hospital, Fort Belvoir, Va.; and General Surgery Resident, Brooke Army Medical Center, Fort Sam Houston, Texas.