Wilhelm Ernst Karl Alexander Friedrich Heinrich Bernhard Albert Georg Hermann (English: William Ernest Charles Alexander Frederick Henry Bernard Albert George Herman) (10 June 1876 – 24 April 1923) was the last Grand Duke of Saxe-Weimar-Eisenach.

He was born in Weimar, the eldest son of Karl August of Saxe-Weimar-Eisenach, heir to the Grand Duke, and his wife Princess Pauline of Saxe-Weimar-Eisenach.

He succeeded his grandfather Karl Alexander as Grand Duke on 5 January 1901, as his father had predeceased him.

His heir was a distant cousin, Prince Hermann of Saxe-Weimar-Eisenach, until his disinheritance in 1909. Hermann's younger brother subsequently served as heir presumptive to the Duchy of Saxe-Weimar-Eisenach until the birth of William Ernest's eldest son.

Wilhelm Ernst created the new Weimar town center under the direction of Hans Olde, Henry van de Velde, and Adolf Brütt. Also, he also had the University of Jena rebuilt by Theodor Fischer, and also reconstructed Weimar's theatres. The improvements to the city included a marble statue of his predecessor Charles Alexander, which was completed in 1911. It was placed in a setting designed by Brütt. The placement of the setting was designed to distinguish the "old town" from the newly built area. A preservation law for the "old town" barred it to the "art nouveau"-style which was used in the new area.

According to the Dutch constitution, Wilhelm Ernst was in the line for the throne of the Netherlands (as the grandson of Princess Sophie of the Netherlands) after Queen Wilhelmina. At the beginning of the 20th century, the Dutch feared the possibility of German influence or even annexation of the Netherlands. In order to prevent this, some lawyers tried to change the constitution to exclude Wilhelm Ernst from the succession. Another proposal, however, was this: if Wilhelmina would die childless, then he or his offspring would have to choose between the Dutch and the Weimar throne. The birth of Wilhelmina's daughter Juliana in 1909 lessened the chance for any member of the house of Wettin (Saxe-Weimar-Eisenach branch) to inherit the Dutch throne. With the amendment to the constitution of 1922, which restricted the right of succession to the offspring of Wilhelmina, the possibility disappeared entirely.

...
Wikipedia