Yusuf, swept irresistibly upwards into the Iberian Peninsula,
recapturing Lisbon and Santarem in the west, and pushing their
conquest as far as the river Mondego.

To meet this revival of Mohammedan power, Alfonso VI. Of Castile
summoned the chivalry of Christendom to his aid. Among the
knights who answered the call was Count Henry of Burgundy
(grandson of Robert, first Duke of Burgundy) to whom Alfonso gave
his natural daughter Theresa in marriage, together with the
Counties of Oporto and Coimbra, with the title of Count of
Portugal.

That is the first chapter of the history of Portugal.

Count Henry fought hard to defend his southern frontiers from the
incursion of the Moors until his death in 1114. Thereafter his
widow Theresa became Regent of Portugal during the minority of
their son, Affonso Henriques. A woman of great energy, resource
and ambition, she successfully waged war against the Moors, and
in other ways laid the foundations upon which her son was to
build the Kingdom of Portugal. But her passionate infatuation for
one of her knights--Don Fernando Peres de Trava--and the
excessive honours she bestowed upon him, made enemies for her in
the new state, and estranged her from her son.

In 1127 Alfonso VII. of Castile invaded Portugal, compelling
Theresa to recognize him as her suzerain. But Affonso Henriques,
now aged seventeen--and declared by the citizens of the capital
to be of age and competent to reign--incontinently refused to
recognize the submission made by his mother, and in the following