[1] In 1065, Geoffrey d'Hauteville, Count of the Capitanata and the brother of Robert Guiscard, conquered the county of Chieti.

His son, Roberto di Loritello, completed the conquest as far as Ortona, thereby bringing the excommunication of Pope Gregory VII on him as a usurper of papal property.

[9] Bishop Theoderic held a diocesan synod in May 840, in which he established a Canonicate in which the priests who served the cathedral of S. Justinus should live and pray together.

[13] Clement wrote a letter to Queen Joanna I of Naples, informing her that some of the clergy of Chieti, led by the Vicar General, were engaged in active physical resistance against his agents, who were attempting to install bishop-elect Tommaso Brancaccio.

[15] Joanna supported Clement VII until a revolution led by Charles of Durazzo deposed her on 25 August 1381, and had her murdered on 27 July 1382.

Urban VI wrote a letter to the people of Chieti in November 1381, in favor of Charles, and declaring Joanna deposed and excommunicated.

[16] Bishop Giovanni Pietro Carafa in 1524 resigned the see of Chieti, and, along with Cajetan of Tiene, founded the Theatine Order.

[23] With their support, Pope Paul issued the bull "Inter Caetera" on 18 July 1539, reversing the arrangement of Clement VII and making the diocese of Penne ed Atri again directly dependent upon the Holy See.

Finally, Pope Pius IV intervened, and, in a bull of 26 February 1562, promoted Lanciano to the status of an archdiocese, directly dependent upon the Holy See.

[28] On 2 March 1982, Pope John Paul II issued the bull, Fructuosae Ecclesiae, in which he created the new ecclesiastical province of Chieti (Theatina), granting it as suffragan dioceses Vasto, Lanciano and Ortona.