outstanding Portuguese military leader, known also as the Holy Constable, whose victory over Castilian forces in the historic Battle of Aljubarrota (Aug. 14, 1385) assured his nation's independence.

Pereira distinguished himself in battle at age 13, fighting against the Castilians in their invasion of 1373. On the death of Ferdinand I of Portugal (October 1383), Pereira came forward as a supporter of John of Aviz (John I), the illegitimate son of Ferdinand's father Peter I, against the claims of Ferdinand's daughter Beatriz, whose marriage to John I of Castile posed a threat to Portugal's independence. In January 1384 John I invaded Portugal. Despite the fact that most of his family favoured Castile, Pereira continued to support John of Aviz (later John I, king of Portugal) and defeated the Castilians in the Battle of Atoleiros (April 6, 1384). Further brilliant and heroic actions as a field commander won him the office of constable of the kingdom in 1385.

Although the Castilians had withdrawn in 1384, they invaded again the following year and moved on Lisbon. Pereira blocked the Castilians at Aljubarrota, won a decisive victory, and continued to fight against them until the final peace of Oct. 30, 1411. He gave all his support to the expedition that captured Portugal's first African possession, Ceuta in northern Morocco, from the Moors in 1415.

John I of Portugal rewarded Pereira with titles and extensive lands and properties. Pereira's daughter Beatriz married John I's legitimated son Afonso and thus became ancestor of the house of Bragança (Bragança, House of), which in 1640 became the ruling house of Portugal. Pereira, who had had a Carmelite house built in Lisbon in fulfillment of a vow, entered it himself as Friar Nuno de Santa Maria in 1423. He was beatified by Pope Benedict XV on Jan. 23, 1918.