[3] Once established in Portugal, the Duke was granted a pension and residence by the Fundação da Casa de Bragança, the organization has owned and managed all the private assets of the House of Braganza, since the death of King Manuel II, in 1932.

In 1942, the Duarte Nuno married Princess Maria Francisca of Orléans-Braganza, daughter of Pedro de Alcântara, Prince of Grão-Pará.

The couple had three sons, the eldest of whom is Duarte Pio de Bragança, the current pretender to the defunct Portuguese throne.

Duarte Nuno's father was the Miguelist claimant to the throne of Portugal who opposed his cousins, the reigning line of the House of Braganza-Saxe-Coburg and Gotha descended from Queen Maria II.

[citation needed] Since Duarte Nuno was only twelve years old when he succeeded as Miguelist claimant to the Portuguese throne, his aunt, the Duchess of Guimarães, acted as regent for him until he attained his majority.

The Miguelists upheld Portugal's tradition of autocratic absolutism, while the Braganza-Saxe-Coburg and Gotha's adhered to constitutional monarchy.

In 1912, Duarte Nuno's father, Miguel Januário, met with Manuel II to try to come to some agreement so that there would not be two claimants to the Portuguese throne, both living in exile.

But the agreements were important steps in reconciling the Miguelist and the Braganza-Saxe-Coburg branches of Portugal's royal family, and helped move the supporters of each toward a united monarchist movement.

Henceforth, the majority of monarchists, both Miguelist and constitutional, supported Duarte Nuno as claimant to the Portuguese throne.

João António de Azevedo Coutinho, the head of Causa Monárquica and Manuel II's lieutenant while he was in exile, published a declaration in support of Duarte Nuno.

However, Dom Duarte's line was banished by law (of the Portuguese Cortes) rather than by judicial sentence (that, in addition, might have been changed by a new judicial sentence); but the 1838 Constitution, in force at the time of the banishment, established D. Miguel I's deprivation of citizenship, and consequently the loss of his hereditary rights to the throne of Portugal, as well as reinforced this 'ad hoc' law of exile, making it almost irrevocable.

Manuel's genealogical heir at his death in 1932 was ex-Crown Prince George of Saxony (a great-grandson of Maria II), but he was not Portuguese; he was also a Catholic priest.

[citation needed] A woman calling herself Maria Pia de Saxe-Coburgo e Bragança claimed to be the bastard daughter of King Carlos I.

[citation needed] On 15 October 1942, in the cathedral of Petrópolis in Brazil, Duarte Nuno married Princess Maria Francisca of Orléans-Braganza (8 September 1914 – 15 January 1968), daughter of Pedro de Alcântara, Prince of Grão-Pará.

Duarte Nuno is buried in the Augustinian monastery in Vila Viçosa, the traditional burial place of the Dukes of Braganza.