Complex sentence: Adoption proved a more flexible and workable tool for orderly succession in the Roman Empire than natural succession did, seeing that it guaranteed that people of promise, and often of proven competence, were named as official successors to what was in effect a military dictatorship.
Split into simpler sentences: Adoption proved a more flexible and workable tool for orderly succession in the Roman Empire than natural succession did. It guaranteed that people of promise, and often of proven competence, were named as official successors to what was in effect a military dictatorship.