Byrne participated in preparations for the 1798 Rebellion, fought at Oulart, Enniscorthy, the Battle of Clough, the Battle of Arklow, the Battle of Vinegar Hill, Castlecomer and Ballygullen at the age of 18. After the Wexford Rebellion was over, he joined Michael Dwyer and Joseph Holt in the Wicklow Hills, continuing to fight on. Next he settled in Dublin. While there he was involved in the Emmet Rebellion. In his Memoirs he describes a meeting he arranged between Robert Emmet and Thomas Cloney at Harold's Cross Green, Dublin, just prior to Emmet's Rebellion: "I can never forget the impression this meeting made on me at the time - to see two heroic patriots, equally devoted to poor Ireland, discussing the best means of obtaining her freedom."
Shortly after this he escaped to France. In France he eventually became Brigadier General and leader of Napoleon’s Irish Legion, and was awarded the Legion of Honour. He fought in Spain and Greece. In his later years he wrote his memoirs, Memoirs of Miles Byrne, which are an account of his participation in the Irish rebellion and his time in the Irish Legion of Napoleon. These were first published in three volumes in 1863, but there have been many subsequent reprints. Stephen Gwynn who edited and published a new edition of Byrne’s Memoirs in 1907, stated in his Introduction to Volume 1: “I owe my acquaintance with these Memoirs to Mr John Dillon, who spoke of them as the best of all books dealing with Ireland; and a reading of the volumes left me inclined to agree with him.” For those areas and battles that it covers, Byrne's is the best source for the 1798 Rebellion. In Paris, Byrne frequently met many other exiled Irish - including Thomas Addis Emmet and James Devereux.
A photograph of Byrne faces page 185 in Nicholas Furlong's "Fr John Murphy of Boolavogue: 1753-1798". According to the author, it was taken in Paris in 1859 and is reputed to be the first photograph taken of an Irishman. The photograph is now in Áras an Uachtaráin, the residence of the President of Ireland, in Dublin. John Mitchel visited Byrne when he was 80 years old and described him as "One of those rare beings who never grow old".
Death
Miles Byrne died at his house in the rue Montaigne, Paris on Friday 24 January 1862, and was buried in Montmartre Cemetery. His grave there is marked by a Celtic Cross - but this headstone appears to be a 1950s replacement for an earlier one. The inscription to his original headstone appears in his Memoirs; in part, it read:
Legacy
He is the great-great grandfather of Miles Patrick Byrne.
