He was the younger brother of Marshal Jean-Baptiste Bessières, Duke of Istria.

[1] After serving with a good record in Italy, in Egypt and at Hohenlinden, Bertrand Bessières had a command in the Grande Armée, fought at Austerlitz and was subsequently promoted to brigadier general.

In 1808 was sent to Spain, where he under General Duhesme in Catalonia[1] and played a notable part at the Battle of Molins de Rei near Barcelona.

Disagreements with his superior, led to his resignation, but he subsequently served with Napoleon in all the later campaigns of the empire and was wounded at Borodino and Leipzig.

His last public act was his defence of the unfortunate Marshal Ney.