Cronica

Cronica was a book written by, obtained by Ezio Auditore da Firenze in the 16th century from Cappadocia's book shop.

Summary
A soldier for much of his life, Catalan mercenary Ramon Muntaner wrote his "Cronica" to memorialize his time as a soldier fighting alongside Byzantine Greeks while protecting Constantinople against besieging Turkish armies.

Reference

 * Assassin's Creed: Revelations