Seven Books of History Against the Pagans (Latin: Historiarum Adversum Paganos Libri VII) is a work of universal history written in the early fifth century by Paulus Orosius, a Galician Catholic priest and student of St Augustine. The History Against the Pagans shares a common aim with Augustine's City of God, in seeking to vindicate Christianity as a positive development in human history, at a time when pagans were blaming the new religion for the sack of Rome by Alaric.
The work enjoyed immense popularity in the Middle Ages, being translated into Old English, reputedly by King Alfred, and into Arabic in Andalusia.
Free online texts
Attalus.org: Historiarum Adversum Paganos Libri VII. Latin HTML text.
Documenta Catholica Omnia: Historiarum Libri Septem. Latin PDF text.
Google Sites/Demontortoise2000: A History Against the Pagans. English HTML text.
Internet Archive: King Alfred's Orosius (Early English Texts Society, 1883). Latin and Old English, multiple formats.
Internet Archive: Historiarum Adversum Paganos Libri VII (1574). Latin text, multiple formats.
Internet Archive: Historiarum Adversum Paganos Libri VII (Syvert Haverkamp, 1857). Latin text, multiple formats.
Internet Archive: Historiarum Adversum Paganos Libri VII (Teubner edition, 1889). Latin text, multiple formats.
Latin Library: Historiarum Adversum Paganos Libri VII. Latin HTML text.
Unversity of Oxford Text Archive: Alfred's Orosius. Old English, ZIP text file.
Academia.edu: The Orosius in King Alfred’s Court: A Ninth-Century Historical Renaissance, by David Carlton.
Ancient History Encyclopedia: Orosius, by Joshua J. Mark.
Catholic Encyclopedia: Paulus Orosius.
Further reading at Tom's Learning Notes
Augustine's City of God - The two texts are closely related as defences of Christianity in the wake of the sack of Rome.
Orosius used a range of sources including: Livy, Caesar's Gallic War, Tacitus, Suetonius, Florus, Eutropius, Justin, Jerome's translation of Eusebius' Chronicle and Rufinus' translation of Eusebius' Ecclesiastical History.