If Y2K proved anticlimactic, the Y1K crisis—apocalyptic expectations surrounding the year 1000—had a lasting impact, argues this far-ranging, over-reaching history of medieval Europe. Holland (Persian Fire
) surveys the two and a half centuries between the fragmenting of Charlemagne's empire and the First Crusade, visiting milestones like the Norman conquest of England along with lesser invasions, raids, feudal vendettas, kidnappings and pope vs. antipope squabbles. He discerns movement amid the tumult and slaughter, as Catholic Europe went from anxious beleaguerment by the barbarians coming from every direction to confident expansionism. Holland's thesis that it was the disappointment of millennial hopes that gave Christendom its new focus on worldly progress is weakly supported; he has a hard time showing that anyone besides churchmen thought about the approaching millennium. His greater theme is Catholicism's civilizing mission: pagan foes are converted and co-opted, a new class of marauding knights is tamed by Church peace councils, and Pope Gregory VII's defiance of Emperor Henry IV inaugurates church-state separation. Holland's colorful, energetic narrative vividly captures the medieval mindset, while conveying the dynamism that underlay a seemingly static age. Maps. (May 5)