Procopius 
History of the Wars by Procopius [EPUB ebook] 

History of three wars from the reign of Justinian, Byzantine emperor — The Persian War, The Vandalic War, and The Gothic War. According to Wikipedia: 'Procopius of Caesarea (Latin: Procopius Caesarensis, c. AD 500 – c. AD 565) was a prominent Byzantine scholar from Palestine. Accompanying the general Belisarius in the wars of the Emperor Justinian I, he became the principal historian of the 6th century, writing the Wars of Justinian, the Buildings of Justinian and the celebrated Secret History. He is commonly held to be the last major historian of the ancient world.’