The earliest regular proof gold coinage years, from 1859 to the end of the Civil War, saw mintages radically in flux, yet a fairly consistent number of pieces sold. Among the more interesting perspectives on this topic is that of Garrett and Guth, who write about this issue in their Encyclopedia of U.S. Gold Coins: 'Although the Mint increased production of Proof eagles to 69 pieces in 1861, the number of pieces sold appears to have been the same amount as in the previous two years. This conclusion is based on the number of survivors, which seems identical for 1859, 1860, and 1861 issues.'