Complex sentence: The Spanish "Reconquista" began later in the eighth century, but the campaign (which eventually took 800 years to force the Moors back across the Strait) did not reach the Bay of Gibraltar until the fourteenth century.
Split into simpler sentences: The Spanish "Reconquista" began later in the eighth century. The campaign eventually took 800 years to force the Moors back across the Strait, and did not reach the Bay of Gibraltar until the fourteenth century.