 Complete the following phrase:  The beginnings of the Portuguese Empire can be traced to 25 July 1415, when the Portuguese Armada set sail for the rich Islamic trading center of Ceuta in North Africa. The Armada was accompanied by King John I, his sons Prince Duarte a future king, Prince Pedro, and Prince Henry the Navigator, and the legendary Portuguese hero Nuno Álvares Pereira. On 21 August 1415, 