Duke of Guarda
However, the majority of historians defend that the Dukedom of Trancoso did not exist, and the confusion comes from the fact that Infante Ferdinand (Fernando, in Portuguese) was also Lord of Trancoso.
Finally, others say he was Duke of Guarda and Trancoso (a jointly Dukedom).
One thing is for sure: Infante Ferdinand was the sole to bear the title of Duke of Guarda.
But when the Infante marriage was announced, the 1st Marquis of Torres Novas (who later became the 1st Duke of Aveiro) declared he had secretly married the richest heir. The scandal in the Court ended when King John III ordered the Marquis imprisonment for several years, allowing the celebration of the Infante Ferdinand's marriage.
In spite of their short but happy marriage, they had two children (a boy and a girl), who died in very young age, before their parents.
List of the Dukes of Guarda
”Nobreza de Portugal e do Brasil” – Vol. I, page 385. Published by Zairol Lda., Lisbon 1989.