The Wild Geese fought for France in the 17th and 18th centuries and Irishmen joined the Papal Brigade to garrison the Vatican in 1860 to deter annexation by Italy following the Second Italian War of Independence.

On 7 September the Committee for the Relief of the Sick and Wounded of the French Army and Navy was founded in Dublin, under the leadership of Father Tom Burke.

[4] The committee decided to raise a medical corps to serve alongside the French armed forces which, as a non-combatant unit, would not contravene the Foreign Enlistment Act.

[5] The unit paraded at Dublin's Rotunda Gardens on 8 October before marching to the docks to embark on the French vessel La Fontaine.

[7] The Franco-Irish Ambulance Brigade arrived at Le Havre on 11 October where it joined the army of the French Third Republic which continued the war with Prussia.

[8][9] A second Irish ambulance unit was raised in London but was turned away upon arrival at Caen as no arrangements had been made with the French authorities to accept it.

[3][8] The brigade subsequently served on the battlefield recovering the wounded and bringing them to casualty clearing stations run by the ambulance where treatments included a large number of amputations and bloodletting by leeches.

[3][11] Upon arrival the detachment with the Army of the Loire was caught up in a crossfire Châteaudun and subsequently established a 60-bed hospital in preparation for the First Battle of Orleans, during which stretcher bearers were sent to the front lines.

[13] They spent Christmas Day at Châteaudun before witnessing General Antoine Chanzy's defeat at the Battle of Le Mans on 12 January which effectively destroyed the army.

[16] Shortly after the destruction of the Army of the Loire the French authorities issued orders to the Franco-Irish Ambulance Brigade releasing them from their duties on 5 January 1871.

[9] The British National Archives holds documents from the time that claim that only 40 of the brigade were taken into service as ambulance men and the remainder become soldiers or else returning home.

[17] The men of the brigade who served in La Compagnie Irlandaise fought well at Montbéliard and in the subsequent retreat to Besançon before the 28 January 1871 Armistice of Versailles brought hostilities to a close.