 Caliph Al-Walid I had paid great attention to the expansion of an organized military, building the strongest navy in the Umayyad Caliphate era (the second major Arab dynasty after Mohammad and the first Arab dynasty of Al-Andalus).It was this tactic that supported the ultimate expansion to Spain.Caliph Al-Walid I's reign is considered as the apex of Islamic power, though Islamic power in Spain specifically climaxed in the 10th century under Abd-ar-Rahman III.