Since the Medal of Honor was established, 19 recipients have received it twice, of whom 5 received both awards during World War I. These 5 men were all Marines who received both the Army and Navy versions of the Medal of Honor for the same action. This was made possible by the practice of attaching some units of the U.S. Marine Corps, a part of the Department of the Navy, to larger U.S. Army commands, making Marines in such units eligible for both Army and Navy decorations. Of the other three Marines who earned the Medal of Honor during World War I, two were awarded only the Navy version and one, Fred W. Stockham, received only the Army version. In February 1919, the criteria for the award were amended to state that no person could receive more than one Medal of Honor, thus precluding any future double recipients.