Principal Officers and Chiefs of Mission, by year: 1866

Note: Career Foreign Service appointees are asterisked.

• Wright, Joseph Albert (1810-1867)
  • Envoy Extraordinary and Minister Plenipotentiary, Germany (1857-1861)
  • Envoy Extraordinary and Minister Plenipotentiary, Germany (1865-1867)
• Williams, Alpheus Starkey (1810-1878)
  • Minister Resident, El Salvador (1866-1869)
• Wilson, James (1825-1867)
  • Minister Resident, Venezuela (1866-1867)
• Adams, Charles Francis (1807-1886)
  • Envoy Extraordinary and Minister Plenipotentiary, United Kingdom (1861-1868)
• Asboth, Alexander (1811-1868)
  • Minister Resident, Argentina (1866-1868)
  • Minister Resident, Uruguay (1867-1868)
• Bigelow, John (1817-1911)
  • Envoy Extraordinary and Minister Plenipotentiary, France (1865-1866)
• Clay, Cassius Marcellus (1810-1903)
  • Envoy Extraordinary and Minister Plenipotentiary, Spain (1861)
  • Envoy Extraordinary and Minister Plenipotentiary, Russia (1861-1862)
  • Envoy Extraordinary and Minister Plenipotentiary, Russia (1863-1869)
• Clay, Thomas Hart (1803-1871)
  • Minister Resident, Nicaragua (1862-1863)
  • Minister Resident, Honduras (1863-1866)
• Coggeshall, William Turner (1824-1867)
  • Minister Resident, Ecuador (1866-1867)
• Burlingame, Anson (1820-1870)
  • Envoy Extraordinary and Minister Plenipotentiary, Austria (1861)
  • Envoy Extraordinary and Minister Plenipotentiary, China (1861-1867)
• Campbell, James Hepburn (1820-1895)
  • Minister Resident, Sweden (1864-1867)
  • Minister Resident, Colombia (1866)
• Campbell, Lewis Davis (1811-1882)
  • Envoy Extraordinary and Minister Plenipotentiary, Mexico (1866)
• Dickinson, Andrew B. (?-?)
  • Minister Resident, Nicaragua (1861-1863)
  • Minister Resident and Extraordinary, Nicaragua (1863-1869)
• Dix, John Adams (1798-1879)
  • Minister Resident, Netherlands (1866)
  • Envoy Extraordinary and Minister Plenipotentiary, France (1866-1869)
• Ewing, Hugh Boyle (1826-1905)
  • Minister Resident, Netherlands (1866-1870)
• Hale, Charles (1831-1882)
  • Agent/Consul General, Egypt (1864-1870)
  • Assistant Secretary of State (1872-1873)
• Hale, John Parker (1806-1873)
  • Envoy Extraordinary and Minister Plenipotentiary, Spain (1865-1869)
• Hall, Allen A. (?-1867)
  • Minister Resident, Bolivia (1863-1867)
• Hanson, Abraham (?-1866)
  • Commissioner and Consul General, Liberia (1863-1866)
• Harrington, George (1815-1892)
  • Minister Resident, Switzerland (1865-1869)
• Harvey, James E. (1820-?)
  • Minister Resident, Portugal (1861-1869)
• Hassaurek, Frederick (Friedrich) (1831-1885)
  • Minister Resident, Ecuador (1861-1866)
• Hovey, Alvin Peterson (1821-1891)
  • Envoy Extraordinary and Minister Plenipotentiary, Peru (1865-1870)
• Hunter, William (1805-1886)
  • Chief Clerk (1852-1855)
  • Secretary of State ad interim (1853)
  • Assistant Secretary of State (1855)
  • Secretary of State ad interim (1860)
  • Second Assistant Secretary of State (1866-1886)
• Kilpatrick, Judson (1836-1881)
  • Envoy Extraordinary and Minister Plenipotentiary, Chile (1865-1870)
  • Envoy Extraordinary and Minister Plenipotentiary, Chile (1881)
• King, Rufus (1814-1876)
  • Minister Resident, Holy See (1861)
  • Minister Resident, Holy See (1863-1867)
• Kirk, Robert C. (1821-?)
  • Minister Resident, Argentina (1862-1866)
  • Minister Resident, Uruguay (1869-1870)
  • Minister Resident, Argentina (1869-1871)
• Marsh, George Perkins (1801-1882)
  • Minister Resident, Turkey (1849-1853)
  • Envoy Extraordinary and Minister Plenipotentiary, Italy (1861-1882)
• McBride, James (1802-1875)
  • Minister Resident, Hawaii (1863-1866)
• McCook, Edward Moody (1833-1909)
  • Minister Resident, Hawaii (1866-1868)
• McGinnis, John (?-?)
  • Minister Resident, Sweden (1866)
• Lawrence, Albert Gallatin (1836-1887)
  • Minister Resident, Costa Rica (1866-1868)
• Morris, Edward Joy (1815-1881)
  • Chargé d'Affaires, Two Sicilies (1850-1853)
  • Minister Resident, Turkey (1861-1870)
• Motley, John Lothrop (1814-1877)
  • Ambassador Extraordinary and Plenipotentiary, Austria (1861-1867)
  • Ambassador Extraordinary and Plenipotentiary, United Kingdom (1869-1870)
• Nelson, Thomas Henry (1824-1896)
  • Envoy Extraordinary and Minister Plenipotentiary, Chile (1861-1866)
  • Envoy Extraordinary and Minister Plenipotentiary, Mexico (1869-1873)
• Peck, Henry Everard (1821-1867)
  • Commissioner and Consul General, Haiti (1865)
  • Minister Resident/Consul General, Haiti (1866-1867)
• Pike, James Shepard (1811-1882)
  • Minister Resident, Netherlands (1861-1866)
• Rhodes, Albert (1840-?)
  • Chargé d'Affaires, Netherlands (1866)
• Riotte, Charles N. (?-?)
  • Minister Resident, Costa Rica (1861-1867)
  • Minister Resident, Nicaragua (1861-1867)
  • Minister Resident, Costa Rica (Not commissioned; nomination tabled by the Senate.)
• Rousseau, Richard Hilaire (1815-1872)
  • Minister Resident, Honduras (1866-1869)
• Sanford, Henry Shelton (1823-1891)
  • Minister Resident, Belgium (1861-1869)
  • Minister Resident, Belgium (Not commissioned; nomination not confirmed by the Senate.)
  • Minister Resident, Spain (Not commissioned; nomination not confirmed by the Senate.)
• Seward, Frederick William (1830-1915)
  • Assistant Secretary of State (1861-1869)
  • Assistant Secretary of State (1877-1879)
• Seward, William Henry (1801-1872)
  • Secretary of State (1861-1869)
• Seys, John (?-?)
  • Minister Resident/Consul General, Liberia (1866-1870)
• Sickles, Daniel Edgar (1825-1914)
  • Minister Resident, Netherlands (1866)
  • Envoy Extraordinary and Minister Plenipotentiary, Spain (1869)
• Van Valkenburgh, Robert Bruce (1821-1888)
  • Minister Resident, Japan (1866-1869)
• Warren, Fitz Henry (1816-1878)
  • Minister Resident, Guatemala (1865-1869)
• Washburn, Charles Ames (1822-1889)
  • Commissioner, Paraguay (1861)
  • Minister Resident, Paraguay (1863-1868)
• Webb, James Watson (1802-1884)
  • Chargé d'Affaires, Austria (1849-1850)
  • Minister Resident, Turkey (1861)
  • Envoy Extraordinary and Minister Plenipotentiary, Brazil (1861-1869)
• Yeaman, George Helm (1829-1908)
  • Minister Resident, Denmark (1865-1870)