General Notes

John I, b.  Apr.  11, 1357, d.  Aug.  14, 1433, ruled Portugal from 1385 to
1433, a period that saw the beginning of Portuguese overseas expansion.  The
illegitimate son of Peter I, John came to the throne in a revolt against the
regency established by the widow of his half brother, Ferdinand I
on behalf of Ferdinand's daughter Beatrice, the wife of John I of Castile.
John's defeat of the Castilians in the Battle of Aljubarrota in 1385
assured Portuguese independence, although a formal peace was not concluded
until 1411.
In 1387, John married Philippa of Lancaster, daughter of John of Gaunt.  Ably
advised by his chancellor, Joao das Regras, and his military commander, Nuno
Alvares Pereira, John strengthened the powers of the monarchy and of the
merchants and lesser nobles at the expense of the higher aristocracy.  Not
content with ruling a stable and prosperous, albeit small, kingdom, John took
advantage of Portugal's maritime position to encourage shipbuilding and
overseas trade.  In 1415 a major expedition seized the strategic harbor and
trading city of Ceuta on the coast of Morocco, and in the 1420s the Portuguese
began to settle the Madeira Islands, stepping-stones toward the South
Atlantic.  John was succeeded as king by his eldest son, Edward I;  John's
sons, especially Henry the Navigator, continued Portuguese patronage of
overseas exploration.