He was pope during a period of violence and disorder in central Italy, when warring aristocratic factions sought to use the material and military resources of the papacy.
[17] With the death of Theodore in 898, Sergius, with a small following of Roman nobility led by his father Benedictus, attempted to have himself elected pope, contrary to the wishes of Emperor Lambert, who was also duke of Spoleto.
[2][3] Sergius accepted, and with the armed backing of Adalbert II, he entered Rome, by which stage Christopher had already been cast into prison by Theophylact.
[27] For centuries it was believed that Sergius then had the much-abused corpse of Formosus exhumed once more, tried, found guilty again, and beheaded, thus in effect conducting a second Cadaver Synod.
[29] Although neither Sergius nor Theophylact supported the continued nominal rule of Emperor Louis the Blind, they were somewhat unwilling to grant the imperial title to the only other contender, Berengar I of Italy.
[30] When Sergius was ignored, the pope wrote to the bishop of Pola in 910, making it clear that: "he would never bestow the (imperial) crown on Berenger till he promised to take the (Istrian) March from Albuinus, and give it to some better man.
[32] He also helped with the rebuilding of Nonantola Abbey, which had suffered attacks from the Magyars,[33] and finally he granted privileges to some monasteries and churches in West and East Francia.
[34] However, the major issue with Constantinople that presented itself during Sergius' pontificate was the question over the fourth marriage of the Byzantine Emperor Leo VI the Wise.
This relationship was promoted by Marozia's mother, Theodora, and the result of this affair was a male child who in time became Pope John XI (931–935).
His recounting of the period has led sixteenth-century cardinal and historian Caesar Baronius in his Annales Ecclesiastici to call it the Saeculum obscurum, or dark century.
[40] Similarly 19th-century Protestant historians saw this period as a "pornocracy", or "rule of the harlots",[41] a reversal of the natural order as they saw it, according to Liber pontificalis and a later chronicler who was also biased against Sergius III.
This "pornocracy" was an age with women in power: Theodora, whom Liutprand characterized as a "shameless whore... [who] exercised power on the Roman citizenry like a man"[This quote needs a citation] and her daughter Marozia, the mother of Pope John XI and reputed to be the mistress of Sergius III, largely upon a remark by Liutprand.
[42] Caesar Baronius, writing in the 16th century, and basing himself on Liutprand, was particularly scathing, describing Sergius as: "a wretch, worthy of the rope and of fire... flames could not have caused this execrable monster to suffer the punishments which he merited.
[46] The best that Ferdinand Gregorovius could say of him was: "That Sergius, who remained Pope throughout the storms of seven years, was at least a man of energy must be admitted, although apostolic virtues are scarcely to be looked for in a character such as his".