John Madden repurchased Sir Martin in late 1919 as a replacement for Sir Martin's ailing sire, Ogden. Sir Martin returned to the United States in 1920 and remained at Hamburg Place Stud as a breeding stallion until his death in 1930. In Kent Hollingsworth's biography of John Madden, Madden is described as having a sentimental attachment to the old stallion, considering him to be one of the two (the other being Grey Lag) best horses he ever bred. Madden died in November 1929, but as part of his will, Sir Martin was not sold and was allowed to remain on the farm as a pensioner. Sir Martin is buried in the famous Hamburg Place equine cemetery in Lexington.
