From the date and location of their deaths, it appears that Francis Barnham and his brother Robert must have died as combatants in the Jacobite War, part of the conflict between Irish Catholics and Protestants which has continued up to the present. Under James II (1633-1701), advantage was taken of the King's Catholicism to reverse the tendencies of the preceding reign. After his flight from England to France (1688), James crossed to Ireland, where, in a parliament, the Acts of Settlement and Explanation were repealed and provision was made for the restoration of expropriated Roman Catholic lands. When William III (1650-1702) landed in Ireland to oppose James, the country divided denominationally, although the real issue was land rather than religion. After his defeat at the Battle of the Boyn (1690) James fled back to France, but his Roman Catholic supporters continued in arms until defeated at Aughrim and obliged to surrender (1691) at Limerick.
The Jacobite position in the summer of 1691 was a defensive one. In the previous year, they had retreated behind the River Shannon, which acted as an enormous moat around the province of Connacht, with strongholds at Sligo, Athlone and Limerick guarding its crossings. From this position, the Jacobites hoped to receive military aid from Louis XIV of France via the port towns and eventually be in a position to re-take the rest of Ireland.
Godert de Ginkell (1st Earl of Athlpone), the Williamite's Dutch general, had breached this line of defence by crossing the Shannon at Athlone - taking the town after a bloody siege. The Marquis de Saint Ruth, the French Jacobite general moved too slowly to save Athlone, as he had to gather his troops from their quarters and raise new ones from Rapparee bands (Irish guerrilla fighters) and the levies of Irish landowners. Ginkel marched through Ballinasloe, on the main road towards Limerick and Galway, before he found his way blocked by St Ruth’s army at Aughrim on the 12th of July 1691.
It was during the fighting leading up to the Battle of Aughrim that the brothers must have met their deaths, both on the same day (14 Feb 1691).