Final answer:
The Christian kingdoms sought to "regain their lost territories and power" through the Reconquista, a socio-political effort cloaked in religious rhetoric to reclaim the Iberian Peninsula from Muslim rulers, culminating in the fall of Granada in 1492.
Step-by-step explanation:
The real purpose of the Christian kingdoms in their Reconquest War against the Muslims was to "regain their lost territories and power." This effort, known as the Reconquista, was a period during which Christian forces sought to reclaim areas of the Iberian Peninsula that had been controlled by Muslim rulers since the early eighth century. Despite presenting the Reconquista as a religious crusade, the undertakings often fulfilled political and socio-economic objectives, with leaders looking to expand their realms and solidify their rule.
The Reconquista began in earnest in the 11th century, paralleling the larger scale of the Crusades, which aimed to capture the Holy Land from Muslim control. Over the centuries, the Christian forces gradually pushed south, culminating in the significant victory at Las Navas de Tolosa in 1212 and ending with the conquest of Granada in 1492. This marked the expulsion of the last Muslim ruler from Spain and ended nearly eight hundred years of Islamic presence in the region.