As the period we call the Middle Ages reached its zenith, the Christian peoples of the West set out to regain lands lost to Muslim armies four centuries earlier, especially the Holy Land. Their counter-attack met with only partial and temporary success, and levied a catastrophic cost on eastern Christendom. The period was filled with fascinating personalities: the brilliant, eccentric theologian Thomas Aquinas, the iron-fisted German emperor Frederick Barbarosa, the crusader king of England Richard the Lionheart, the most popular saint in history Francis of Assisi, the saintly king of France Louis IX, the scandalous queen consort Eleanor of Aquitaine. Looming over the era stood the soaring walls of massive new stone castles and stately Gothic cathedrals.