He served as chief of staff to Alexandros Mavrokordatos in the disastrous Battle of Peta on 16 July 1822, and died of his wounds a few months later at Missolonghi.
His reputation for honour, kindliness, and fairness, is expressed in a series of letters addressed to him from Missolonghi by Lord Byron early in 1824, which are preserved in Moore's ‘Life of Lord Byron.’ Barff was counted on to manage funds and provide support for Englishmen in Greece.
After the Souliotes defeated the forces of Khourshid Pasha in May and June 1822, they joined Prince Alexander Mavrocordatos who landed at Missolonghi with a contingent of Greek regulars.
Lucca Vaya, physician to Ali Pasha, afterwards to Prince Mavrocordato; educated in Vienna, he was among those treating Lord Byron at Missolonghi.
Eel (Anguilla anguilla), four species of Mugilidae (Liza saliens, Liza aurata, Liza ramada and Mugil cephalus), two species of Sparidae (Sparus aurata and Diplodus annularis) and one species of Mullidae (Mullus barbatus) represent more than 92% of the total annual landings.
The Ottoman army arrived before Missolonghi and began the siege on 20 September with a bombardment of Aitoliko, an island which controlled the seaways of the Missolonghi lagoon.