“ It is therefore announced that in future appointments, details, transfers, and assignments in the Army and Navy, the Executive will be guided by the official records of the War and Navy Departments, respectively, to the exclusion of other sources of influence or information; but in case an officer has performed any special act of bravery or courage or rendered specially efficient service of which there is no record or only a partial record in the War or Navy Department, the testimony of any person who was an eyewitness of the same may be submitted for consideration. ”