The Royal Italian Army (Italian: Regio Esercito, lit. 'Royal Army', abbreviated RE) was the land warfare branch of the armed forces of the Kingdom of Italy from 1861 until 1946. It was established following the proclamation of the Kingdom of Italy during the unification of Italy, largely incorporating the military forces of the Kingdom of Sardinia and annexed Italian states. Following the abolition of the monarchy after the 1946 Italian institutional referendum, the army was reorganized as the modern Italian Army (Esercito Italiano).
The Royal Italian Army played a major role in the political, colonial, and military history of modern Italy. Throughout its existence, it participated in the final campaigns of Italian unification, colonial conflicts in Africa and the Middle East, both world wars, and numerous overseas expeditions. The army was also home to several elite formations, including the Alpini, Bersaglieri, and Folgore units, many of which continue to exist within the modern Italian Armed Forces.
The Royal Italian Army was established in 1861 following the unification of several Italian states under the House of Savoy. The new army was primarily formed from the military forces of the Kingdom of Sardinia, though units and personnel from annexed states, including the Army of the Two Sicilies, were gradually incorporated into the national military structure.
One of the army's earliest responsibilities was suppressing resistance in southern Italy during the period known as Post-unification Italian brigandage. Royal Italian Army forces fought against Bourbon loyalists, separatists, criminal bands, and rural insurgents across southern Italy in a prolonged and violent conflict that lasted throughout much of the 1860s. The army also participated in the final campaigns of Italian unification, including the Third Italian War of Independence in 1866 and the Capture of Rome in 1870, which completed the incorporation of most of the Italian peninsula into the Kingdom of Italy.
During the late 19th century, the Royal Italian Army became increasingly involved in Italy's colonial expansion in Africa. Italian troops participated in campaigns in Eritrea, Somalia, and Libya, as well as military operations during the Mahdist War in Sudan.
The army fought in the First Italo-Ethiopian War of 1895–1896, which ended in the decisive Italian defeat at the Battle of Adwa. The battle became one of the most significant anti-colonial victories of the era and represented one of the first major defeats of a European colonial army by an African state during the modern imperial period.
Italy nevertheless continued expanding its colonial influence. During the Italo-Turkish War of 1911–1912, the Royal Italian Army helped conquer Libya and the Dodecanese islands from the Ottoman Empire. The conflict also marked one of the earliest military uses of aircraft for reconnaissance and aerial bombing.
During World War I, the Royal Italian Army fought primarily against Austria-Hungary along the Italian Front. Much of the fighting occurred in mountainous terrain along the Isonzo River, the Dolomites, and the Alps, where harsh weather and difficult geography contributed to extremely high casualty rates.
Under Chief of Staff Luigi Cadorna, the army launched multiple offensives during the Battles of the Isonzo, though most resulted in limited territorial gains at heavy cost. In 1917, Italian forces suffered a major defeat at the Battle of Caporetto, forcing a large-scale retreat and creating a national crisis. Following Cadorna's removal, General Armando Diaz reorganized the army and improved defensive coordination and troop morale. Italy later contributed to the defeat of Austria-Hungary during the Battle of Vittorio Veneto in 1918.
Within the Royal Italian Army were the elite mountain infantry units known as the Alpini, founded in 1872. The Alpini are considered the oldest active mountain infantry force in the world and were originally tasked with defending Italy's alpine borders with France and Austria-Hungary. During World War I, the Alpini fought in extreme alpine conditions against the Austro-Hungarian Kaiserjäger and the German Alpenkorps, gaining a reputation for endurance and specialized mountain warfare.
Following World War I, the Royal Italian Army underwent significant restructuring amid economic instability and political unrest. During the rise of Benito Mussolini and the National Fascist Party, the army became increasingly tied to Fascist military expansion and nationalist ideology.
In the 1930s, the army participated in the Second Italo-Ethiopian War, which resulted in the conquest of Ethiopia and the creation of Italian East Africa. Italian forces also intervened in the Spanish Civil War in support of Francisco Franco's Nationalist forces and occupied Albania in 1939.
Although the army expanded considerably during the interwar period, modernization efforts remained inconsistent. Many units continued using outdated artillery, transport systems, rifles, and armored vehicles entering World War II, limiting operational effectiveness compared to other major European powers.
During World War II, the Royal Italian Army fought in campaigns across North Africa, the Balkans, mainland Europe, and the Eastern Front. Italian troops participated in the Italian invasion of Greece, the North African campaign, the invasion of Yugoslavia, and the Axis invasion of the Soviet Union.
Despite fielding millions of soldiers, the army faced severe logistical and industrial limitations. Many formations suffered from shortages of modern tanks, motor vehicles, aircraft support, winter equipment, and ammunition. Coordination between branches of the armed forces was often poor, and Italian industry struggled to sustain prolonged mechanized warfare.
Elite formations such as the Alpini, Bersaglieri, and Folgore nevertheless earned reputations for combat effectiveness and resilience in difficult conditions. The Alpini suffered devastating losses during the Soviet winter campaigns, particularly during the retreat following the destruction of the Italian Eighth Army in 1942–1943. The 185th Paratroopers Division Folgore also became notable for its defense during the Second Battle of El Alamein.
Italian military defeats in Greece, Libya, and the Soviet Union gradually weakened the country's strategic position. Following the Allied invasion of Sicily and the overthrow of Mussolini in 1943, the Italian government signed the Armistice of Cassibile with the Allies.
Following the armistice in September 1943, the Royal Italian Army rapidly disintegrated in many regions as German forces occupied much of Italy and disarmed Italian troops. Large numbers of soldiers were captured by Germany, while others escaped, joined partisan resistance groups, or aligned themselves with either the Allied-backed government in southern Italy or the German-supported Italian Social Republic in the north.