Eustathios, bishop of Thessaloniki, wrote a vivid, firsthand account of the sack of Thessaloniki by the Normans of Sicily shortly after the city was captured in 1185. The work opens with a discussion of how the writing of one who experienced a disaster will necessarily differ from that of a dispassionate historian. Eustatios claims that he writes from the honest perspective of a participant and sufferer rather than a rhetorically artful historian. Eustathios's account combines complex sentences and allusions to classical Greek authors with more everyday expressions and scriptural quotations.

After an opening lamentation for the sack of the city and invective against its incompetent commander, David Komnenos, Eustathios goes back to take up the narrative of the accession of Andronikos II (1183– 1185) and the early years of his reign. Eustathios's portrait of Andronikos is deeply negative, highlighting in particular Andronikos's brutal treatment of the Byzantine nobility. Eustathios then turns his attention to the campaign launched by William II of Sicily (1155– 1189), whose army entered Thessaloniki after a brief siege, in large part the result, Eustathios argues, of the incompetent defense mounted by David Komnenos. The narrative then describes the sufferings of Thessaloniki's population at the hands of the conquerors and Eustathios's own experiences, including his efforts to mitigate the conquerors’ treatment of his fellow citizens.

Although Eustathios is a well- known figure of the twelfth century, many of whose letters and rhetorical works survive, scholars have found it difficult to reconstruct a precise biography. His year and place of birth are not known. Typical estimates have ranged between 1110 and 1115. His letters indicate that he was educated in Constantinople and embarked on an ecclesiastical career, beginning as a minister in the Church of St. Euphemia and later – around the 1160s – serving as a deacon for the patriarch. During this time he was active as a teacher and mostly likely wrote his famous commentaries on the Iliad and the Odyssey, along with other commentaries on ancient authors. Around 1168, he attained the high rank of maistōr tōn rhētor ōn, which also included duties in the imperial court.