Gut/Amt Rethwisch
Originally an adlige Gut, Rethwisch became an Amt in 1616, when it was assigned to the spin-off Duchy of Schleswig-Holstein-Sonderburg. When the Holstein portion of that duchy was further spun off into the Duchy of Schleswig-Holstein-Sonderburg-Plön in 1623, Rethwisch went with it. Finally, in 1671, Rethwisch itself was spun off as a separate duchy (after being enhanced by the addition of Benstaben, Klein Schenkenberg, Klein Wesenberg, and Meddewadde from Amt Reinfeld and Klein Boden from Amt Steinhorst in Saxe-Lauenburg).
In 1729, the Rethwisch line died out and the Amt reverted to Holstein-Plön. When the Plön line died out in 1762, Rethwisch reverted to the core Holstein duchy (Holstein-Glückstadt until 1773; just Holstein thereafter), which had already confiscated the original Sonderburg duchy in 1668. When Holstein exchanged territory with the Principality of Lübeck in 1843, the villages of Groß- and Klein Barnitz were included and were assigned to Amt Rethwisch.
List of villages in Amt Rethwisch
- Altenweide 1544 - 1864
- Benstaben 1671 - 1864
- Groß Barnitz 1843 - 1864
- Klein Barnitz 1843 - 1864
- Klein Boden 1671 - 1864
- Klein Schenkenberg 1671 - 1864
- Klein Wesenberg 1671 - 1864
- Meddewadde 1671 - 1864
- Rethwischdorf 1544 - 1864
- Rethwischfeld 1544 - 1864
- Sehmsdorf 1544 - 1864
- Steensrade 1544 - 1864
- Tralauerholz 1544 - 1864
- Treuholz 1544 - 1864
Chronological list of countries to which Amt Rethwisch belonged
- Duchy of Holstein (jointly-ruled) 1544 - 1616
- Duchy of Schleswig-Holstein-Sonderburg 1616 - 1623
- Duchy of Schleswig-Holstein-Sonderburg-Plön 1623 - 1671
- Duchy of Schleswig-Holstein-Sonderburg-Plön-Rethwisch 1671 - 1729
- Duchy of Schleswig-Holstein-Sonderburg-Plön 1729 - 1762
- Duchy of Holstein (-Glückstadt) 1762 - 1773
- Duchy of Holstein (unified) 1773 - 1864