The Donatist Communion was a most serious division in the North African Church. The actual separation occurred in Constantine’s reign ; but the circumstances causing it arose earlier out of Diocletian’s persecution. The first eighteen years of Diocletian’s lengthy reign formed for the Church at large a period of comparative peace. Persecutions, indeed, occurred in the dominions of one or other of the four rulers under whose administration the Empire was divided. But these attacks were only local and intermittent. Whatever the predilections of the subordinate Caesars, the old Emperor himself was, for political reasons, of a tolerant disposition. Christianity was believed in his palace and even in his family. Prisca, his wife, Valeria, his daughter, were, more or less distinctly, of the Christian faith. Christian convictions also prevailed among his most trusted servants. And the religion, thus existing in close proximity to the imperial presence, developed also in wider circles among the leading officials of the Empire at large. All this could scarcely be unknown, and it was tolerated for eighteen years. Then came a sudden change.
This book is available via Internet Archive, and was noticed in Donatismus too.