Schwarzburg, either of two sovereign states in Germany before 1918, descended from the Thuringian lands that had been held by the medieval counts of Schwarzburg. Over the centuries the Schwarzburg lands were divided, redivided, or consolidated until the lines of Schwarzburg-Sondershausen and Schwarzburg-Rudolstadt emerged in 1584. The counts of Schwarzburg-Sondershausen were recognized as princes of the Holy Roman Empire in 1697 and those of Schwarzburg-Rudolstadt in 1710. Both principalities, as sovereign states, entered the Confederation of the Rhine in 1807 and the German Confederation in 1815. Both states declared themselves for Prussia in the Seven Weeks’ War and entered the North German Federation (1866) and the German Empire (1871). On the death of the childless Charles Günther of Sondershausen in 1909, both states came under the rule of Günther Victor of Rudolstadt, in personal union. On the German Revolution of 1918, the prince abdicated, and both states became republics before merging themselves, in 1920, in the new state of Thuringia (Thüringen).