Wilhelm IV became grand duke on the death of his father on 17 November 1905, and Marie Anne became grand duchess. Because Wilhelm was the last
agnate of the House of Nassau, he had
Marie-Adélaïde confirmed and proclaimed
heir presumptive on 10 July 1907. Marie Anne was regent for her husband during his terminal illness from 19 November 1908 to 15 February 1912. She then continued as regent for her daughter, Grand Duchess Marie-Adélaïde, during her minority from 25 February 1912 to 18 June 1912. Marie-Adélaïde eventually abdicated in favor of her younger sister, Marie Anne's second daughter
Charlotte in 1919. During
World War II the
grand ducal family left Luxembourg shortly before the arrival of
Nazi troops, settling in France until their capitulation, in June 1940. Subsequently, the family and Grand Duchess Charlotte's ministers received transit visas to Portugal from the Portuguese consul
Aristides de Sousa Mendes, in June 1940. After travelling through Coimbra and Lisbon, the family first stayed in
Cascais, in Casa de Santa Maria, owned by Manuel Espírito Santo, who was then the honorary consul for Luxembourg in Portugal. By July they had moved to Monte Estoril, staying at the Chalet Posser de Andrade. Marie Anne stayed in Monte Estoril with her daughter, the Grand Duchess Charlotte, until 3 October 1940. On the same day, they boarded the Pan Am Yankee Clipper headed for New York City, from where they then left for Canada. With them travelled Prince Félix's aide de camp
Guillaume Konsbruck, his wife Nelly and their sons, Guy and Carlo. ==Death==