[Footnote 49: The Venetian historians, John Sagorninus,
(Chron. Venet. p. 13,) and the doge Andrew Dandolo,
(Scriptores Rer. Ital. tom. xii. p. 135,) have preserved
this epistle of Gregory. The loss and recovery of Ravenna
are mentioned by Paulus Diaconus, (de Gest. Langobard, l.
vi. c. 42, 54, in Script. Ital. tom. i. pars i. p. 506,
508;) but our chronologists, Pagi, Muratori, &c., cannot
ascertain the date or circumstances]