Leopold IV, Prince of Lippe was the final sovereign of the Principality of Lippe. Succeeding to the throne in 1905 he had been governing the state since 1904 as regent.
Since 1895, Lippe had been ruled by a regent due to the incapacity of Prince Alexander. Leopold's father had acted as regent since 1897, and following his death on 26 September 1904, Leopold assumed the regency. This was not recognized by the German Emperor William II, who initially refused to legally recognize Leopold as regent as there was an issue over whether Leopold and his siblings were of legitimate rank, and as such eligible for the succession. As a result, the Diet of Lippe appointed a high commission to consider the matter. The regency issue was still ongoing when Prince Alexander died on 13 January 1905. Leopold was confirmed as Prince of Lippe and Alexander's successor on 25 October 1905, following a court ruling. On 3 June 1911, while out motoring, Leopold and his brother Prince Julius were attacked by a gang of Italian laborers who hurled a shower of missiles at the princes. Though Leopold escaped unhurt, his brother received a head wound. During World War I, Leopold upgraded the titles of the various lines of the House of Lippe. One of the members to benefit from the granting of titles was Leopold's nephew Count Bernhard of Biesterfeld, who would go on to become the Prince Consort of Queen Juliana of the Netherlands. On 24 February 1916, Bernhard and his brother were upgraded to the title Prince of Lippe-Biesterfeld with the style Serene Highness. The Counts of Lippe-Weissenfeld also benefited with creations of the title Prince of Lippe-Weissenfeld, with the style Serene Highness, taking place on 24 February 1916 for Count Clemens and his descendants, and again on 9 November 1918 for the other members of this line. Just three days after upgrading the titles of members of the Lippe-Weissenfeld line, and following the German Empire's defeat in World War I and the subsequent revolution, Leopold was forced to renounce the throne on 12 November 1918. Following the end of his rule, the Principality of Lippe was transformed into a Free state in the new Weimar Republic.
Post abdication
After the rise of Nazism in Germany all three of his sons by his first wife became members of the party. His eldest son the Hereditary Prince Ernst is reported to have been the first German prince to join the party when he signed up in May 1928. In addition to being pro Nazis both Hereditary Prince Ernst and Prince Chlodwig had contracted unequal marriages. So in 1947 when Leopold wrote his will, Armin, his youngest son and only child with his second wife, would succeed him as head of the House of Lippe and also become administrator of the princely family's properties such as Schloss Detmold. Thus when Leopold died in Detmold his three eldest sons were all disinherited and his youngest son Armin became head of the princely house.
