Princess Isabella of Brasland
From NSWiki
Princess Isabella of Brasland (1920-1943) was the daughter of King Frederick V and Princess Maria Anna of Brasland.
In 1940 she married her cousin, Count Henri de Pottin. They had a daughter, Aliénor de Pottin, born in 1942.
Isabella died suddenly in 1943, while she was playing tennis. Her death came as a shock to the royal family, as she was a very active and lively woman.
