British retreat

In the headlong flight of thousands of British soldiers, massive quantities of guns and equipment were abandoned, among which was General Lake's personal luggage. Although not pursued a mile or two beyond Castlebar, the British did not stop until reaching Tuam, with some units fleeing as far as Athlone in the panic. The panic was such that only the arrival of Cornwallis at Athlone prevented further flight across the Shannon.

Although achieving a spectacular victory, the losses of the French and Irish were high, losing about 150 men, mostly to the cannonade at the start of the battle. The British suffered over 350 casualties of which about 80 were killed, the rest either wounded or captured, including perhaps 150 who joined the republicans. Following the victory, thousands of volunteers flocked to join the French who also sent a request to France for reinforcements and formally declared an Irish Republic.
By Naoise