Marie-Adélaide was Grand Duchess of Luxembourg for a handful of years in the early 20th Century, significantly ruling during the First World War.

She was born on June 14, 1894, in Berg Castle, in Colmar-Berg. Her father was the eventual William IV, and her mother was Marie Anne of Portugal. Marie-Adélaide was their oldest child.

She was 11 when her grandfather, the reigning Grand Duke, died, and her father took over rule of the grand duchy. A mere five years later, he died, and she took over. She was 17.

Her mother served as regent for a few weeks, until the Grand Duchess turned 18; then, she ruled in her own right. Unlike her father, she was intensely interested in the goings-on in government and, unlike some of her predecessors, often spent a good deal of time studying bills sent to her for approval before signing them.

Like Belgium, Luxembourg prided itself on its neutrality and did not join the entangling alliances that helped precipitate World War I. However, as with Belgium, Germany ignored Luxembourg's neutrality in its westward march at the outset of the war, professing a need to protect the railroads. Marie-Adélaide and her government screamed internationally in protest but did not attempt to oust the occupying army using force. Luxembourg had rather a small armed force, anyway, and did little to contribute to the war effort on the battlefields. The one exception was in the Red Cross tents, where the grand duchess herself led health and relief efforts. She also angered leaders within her government by, in order to bypass gridlock, dissolving the Chamber of Deputies and scheduling new elections, in 1915.

As the war wound down, calls for her to step aside became more frequent. She had dismissed them initially as political maneuvering but, in the face of fierce criticism internally and internationally after the end of the war, she decided to abdicate. The final impetus was the proclamation of a republic by a group of parliamentary Deputies. She stepped aside on Jan. 14, 1919, and her younger sister Charlotte took over.

Marie-Adélaide left the country in her sister's hands, deciding to travel through Europe instead. In 1920, she decided to join a convent, in Modena, Italy. She was a nun for a few years but then, her health failing, moved to Bavaria. She contracted influenza, and that killed her, on Jan. 24, 1924, in Schloss Hohenburg. She had not married and had no children.