Which factor most unified western europe during the middle ages

After the collapse of the western Roman Empire, the main unifying force in Europe was the Catholic Church

Explanation:

d. japan's attack on pearl harbor

montesquieu took the view that the roman republic had powers separated so that no one could usurp complete power. in the british constitutional system, montesquieu discerned a separation of powers among the monarch, parliament, and the courts of law.