The Armée d'Orient (AO) was a Field army of the French Army during World War I who fought on the Macedonian Front.
One of the French Revolutionary armies, the Army of the Pyrenees ("Armée des Pyrénées") was created by a decree of the National Convention dated 1 October 1792 and formed out of the right wing of the Armée du Midi.
 At the outbreak of the War of the Pyrenees with the Kingdom of Spain, a decree of 30 April 1793 separated the Armée des Pyrénées into the Army of the eastern Pyrenees ("Armée des Pyrénées orientales") and the Army of the western Pyrenees ("Armée des Pyrénées occidentales").
The Macedonian Front of World War I, also known as the Salonica Front (after Thessaloniki), was formed as a result of an attempt by the Allied Powers to aid Serbia, in the fall of 1915, against the combined attack of Germany, Austria-Hungary and Bulgaria.
 The expedition came too late and in insufficient force to prevent the fall of Serbia, and was complicated by the internal political crisis in Greece (the "National Schism").
 Eventually, a stable front was established, running from the Albanian Adriatic coast to the Struma River, pitting a multinational Allied force against the Bulgarian Army, which was at various times bolstered with smaller units from the other Central Powers.
 The Macedonian Front remained quite stable, despite local actions, until the great Allied offensive in September 1918, which resulted in the capitulation of Bulgaria and the liberation of Serbia.
The Army of the West ("armée de l'Ouest") was one of the French Revolutionary Armies.
 It was created on 1 August 1793 by merging the armée des côtes de Brest, the armée des côtes de La Rochelle, and the armée de Mayence, and was sent to fight the revolt in the Vendee.
I Cavalry Corps (Grande Armée) was a French military formation that existed during the Napoleonic Wars.
 For one month in 1806–1807, Emperor Napoleon split his Reserve Cavalry Corps into the I and II Cavalry Corps.
 At that time, Marshal Joachim Murat took command of the short-lived I Cavalry Corps before resuming leadership over Napoleon's Reserve Cavalry when the experiment ended.
 The I Cavalry Corps was not recreated until 1812 for the French invasion of Russia when command was exercised by Étienne Marie Antoine Champion de Nansouty.
 The formation fought at Borodino and Tarutino.
 After being destroyed during the retreat from Russia, I Cavalry Corps was reconstituted in 1813 and Marie Victor de Fay, marquis de Latour-Maubourg was appointed to lead it.
 The corps fought at Lutzen, Bautzen, Dresden, and Leipzig.
 At Leipzig, Latour-Maubourg was seriously wounded and replaced by Jean-Pierre Doumerc who led the corps for the remainder of the War of the Sixth Coalition which ended with Napoleon's abdication in 1814.
 After Napoleon returned from exile and retook power in France in 1815, the main French army was baptised Armée du Nord.
 The army included a I Cavalry Corps led by Pierre Claude Pajol which fought at Ligny and Wavre, while one detached division fought at Waterloo.
Elzéar Auguste Cousin de Dommartin (26 May 1768 in Dommartin-le-Franc – 9 August 1799 in Rosetta) became a French general during the French Revolutionary Wars, fought in Italy under Napoleon Bonaparte, and commanded the artillery division of the Armée d'Orient during the French invasion of Egypt in 1798.
The Army of the Midi ("Armée du Midi") was a unit of the French army, stationed in the Midi region and created by royal decree of Louis XVI on 13 April 1792.
 It existed under this name for less than five months, and was split by a decree of the National Convention dated 1 October 1792 into the "Armée des Alpes" and the "Armée des Pyrénées".
 Another "Armée du Midi" was later gathered by Napoleon for the Peninsular War.
The Armée d'Orient (English: "Army of the Orient") was the French military force gathered by the French Directory to send on the expedition to Egypt in 1798.
 The expedition had the intention of barring Great Britain's route to its colonies in India and was put under the command of Napoleon Bonaparte.
 Also known as Battle of Orient.
The Battle of Mandora was fought on 13 March 1801 between the French Armée d'Orient and the British expeditionary corps, during the French campaign in Egypt and Syria.
The Algerian People’s National Armed Forces (Armée nationale populaire) is the armed forces of the People's Democratic Republic of Algeria.
 Algeria has a large military to counter foreign and domestic threats.
 It is the direct successor of the Armée de Libération Nationale (ALN), the armed wing of the nationalist National Liberation Front, which fought French colonial rule during the Algerian War of Independence (1954-1962).

Question: The Armée d'Orient fought on the front that was created as an aid to what country?
Answer: Serbia