Wikipedia
Sebastianism
Sebastianism, one aspect of the sleeping king folk-motif, is part of the Portuguese and Brazilian mythology and culture. It means waiting for a hero that will save Portugal and lead it to the Fifth Empire, and known as Eu nacional (national Self). In Brazil the most important presence of Sebastianism happened in context of Proclamation of Republic, to lead movements such as the War of Canudos that defended the divine rights of D. Pedro II to rule Brazilian Empire.
Fernando Pessoa also wrote about this hero-to-come in his epic Mensagem (The Message) supporting his ideas on predictions and myths.