14 U.S.C. § 291 : US Code - Section 291: Voluntary retirement after twenty years' service

Search 14 U.S.C. § 291 : US Code - Section 291: Voluntary retirement after twenty years' service

Any regular commissioned officer who has completed twenty years'
active service in the Coast Guard, Navy, Army, Air Force, or Marine
Corps, or the Reserve components thereof, including active duty for
training, at least ten years of which shall have been active
commissioned service, may, upon his own application, in the
discretion of the President, be retired from active service.