Sayn-Wittgenstein-Hachenburg (sometimes called Sayn-Hachenburg) was a German County located in Rhineland-Palatinate, near the river Sieg.
| Conventional Long Name: | County of Sayn-Wittgenstein-Hachenburg |
| Common Name: | County of Sayn-Hachenburg |
| Era: | Early Modern Period |
| Empire: | Holy Roman Empire |
| Government Type: | Feudal County |
| Year Start: | 1648 |
| Year End: | 1827 |
| P1: | Sayn-Wittgenstein-Sayn |
| Flag P1: | RU Furst Sayn-Wittgenstein-Berleburg.png |
| Image Map Caption: | The county in 1805 |
| Leader1: | Ernestine Salentine (first) |
| Leader2: | Louise Isabelle (last) |
| Year Leader1: | 1648–1661 |
| Year Leader2: | 1776–1827 |
| Title Leader: | Countess of Sayn-Hachenburg |
| Today: | Rhineland-Palatinate |
When Count William III of Sayn-Wittgenstein-Sayn died in 1623 without clear heirs, the Archbishop of Cologne occupied the vacant County until the succession was settled. It was settled by treaty in 1648, when the county was given jointly to Countesses Ernestine and Johanetta, two sisters who were granddaughters of Count William, and their mother Dowager Countess Louise Juliane made regent. But shortly after the treaty, the county was split between the two. Ernestine's portion was called "Sayn-Wittgenstein-Hachenburg". Johanetta's was "Sayn-Wittgenstein-Sayn-Altenkirchen" (or Sayn-Altenkirchen for short). Their mother remained regent for both counties until 1652, when Johanetta and Ernestine separately ruled their respective Counties. Sayn-Wittgenstein-Hachenburg was inherited by Countess Magdalena Christina in 1661 following Ernestine's death. It passed to the in 1715, and to the Princes of Nassau-Weilburg in 1799.[1] The title passed through the female line and is held by the Grand Duke of Luxembourg.