Dom Luís Filipe, Prince Royal of Portugal, Duke of Braganza was the eldest son and heir-apparent of King Carlos I of Portugal. He was born in 1887 when his father was still Prince Royal of Portugal and received the usual style of the heirs to the heir of the Portuguese crown: 4th Prince of Beira at birth, with the subsidiary title 14th Duke of Barcelos. After his grandfather King Luís I of Portugal died, he became Prince Royal of Portugal with the subsidiary titles 21st Duke of Braganza, 20th Marquis of Vila Viçosa, 28th count of Barcelos, 25th count of Ourém, 23rd count of Arraiolos and 22nd count of Neiva.

Dom Carlos I, known as the Diplomat, the Martyr, and the Oceanographer, among many other names, was King of Portugal from 1889 until his assassination in 1908. He was the first Portuguese king to die a violent death since King Sebastian in 1578.