Near the beginning of Book 8 of Church History, Eusebius describes the Roman Empire, under Diocletian, launching its fiercest attack on Christians:

In March of the nineteenth year of Diocletian's reign, when the festival of the Savior's passion [Easter] was approaching, an imperial edict was announced everywhere ordering that the churches be demolished and the Scriptures destroyed by fire. Any [Christians] who held high places would lose them, while those in households would be imprisoned if they continued to profess Christianity. Such was the first decree against us.

Soon, however, other edicts appeared ordering that the presidents of the churches everywhere be thrown into prison and then forced by every sort of device to offer sacrifice [to the Emperor].

Then it was that many church leaders endured terrible torments heroically, while countless others succumbed to the first assault, cowardice having numbed their souls. As to the rest, each was subjected to a series of various tortures: one was scourged mercilessly, another racked and scraped to death. People emerged from the ordeal in different ways: one man would be shoved at the loathsome, unholy sacrifices and dismissed as if he had sacrificed when he had not; another who came nowhere near any such abomination but was said to have sacrificed would leave in silence at the falsehood. Still another, half dead, would be discarded as a corpse, while a man who had sacrificed willingly was nevertheless dragged a long distance by his feet. One man would shout at the top of his voice that he had not sacrificed and never would, while yet another would proclaim that he was a Christian and glory in the Savior's name. These were silenced by a large band of soldiers, who struck them on the mouth and battered their faces. The overriding goal of the enemies of godliness was to appear to have accomplished their purpose.

By the beginning of Book 9, Emperor Diocletian had been succeeded by Galerius, who advanced the persecutions. But then Galerius fell ill with a horrible bowel disease and recanted the anti-Christian edicts. Eusebius celebrates:

When this had been done, it was as if a light had suddenly blazed out of a dark night. In every city, churches were thronged, congregations crowded, and rites duly performed. All the unbelieving heathen were astonished at the wonder of so great a transformation and hailed the Christians' God as alone great and true. Among our own people, those who had valiantly contended through the ordeal of persecution again enjoyed freedom with honor, but those whose faith had been anemic and their souls in turmoil eagerly sought healing, begging the strong to extend the right hand of rescue and imploring God to be merciful to them. Then, too, the noble champions of godliness, released from their misery in the mines, returned to their own homes, rejoicing and beaming as they went through every city, exuding an indescribable delight and confidence. Crowds of men went on their way, praising God with hymns and psalms in the middle of the thoroughfares and public squares.

Those who a little earlier had been prisoners, cruelly punished and driven from their homelands, now regained their own hearths with smiles of elation, so that even those who had thirsted for our blood saw this unexpected wonder and shared our joy at what had happened.

— from Eusebius, Church History, 8.2, 8.3, and 9.1. Translated by Paul Maier (Kregel, 1999).

Taken from Eusebius: The Church History © 1999 by Paul L. Maier. Published by Kregel Publications, Grand Rapids, MI. Used by permission of the publisher. All rights reserved.