The Ogaden War, or the Ethio-Somali War (Somali: Dagaalkii Xoraynta Soomaali Galbeed, Amharic: , romanized: yetiyopiya somalya torineti), was a military conflict fought between Somalia and Ethiopia from July 1977 to March 1978 over the Ethiopian region of Ogaden. Somalia's invasion of the region, precursor to the wider war, met with the Soviet Union's disapproval, leading the superpower to end its support of Somalia and support Ethiopia instead.

Ethiopia was saved from defeat and permanent loss of territory through a massive airlift of military supplies worth $1 billion, the arrival of more than 12,000 Cuban soldiers and airmen sent by Fidel Castro to win a second African victory (after his first success in Angola in 197576), and 1,500 Soviet advisors, led by General Vasily Petrov. On 23 January 1978, Cuban armored brigades inflicted the worst losses the Somali forces had ever taken in a single action since the start of the war.The Ethiopians and Cubans (equipped with 300 tanks, 156 artillery pieces and 46 combat aircraft) prevailed at Harar, Dire Dawa and Jijiga, and began to push the Somalis systematically out of the Ogaden. By 23 March 1978, the Ethiopians and Cubans had recaptured more than two-thirds of the Ogaden, marking the official end of the war. A third of the Somali National Army had been killed and half of the Somali Air Force destroyed. The war left Somalia with a disorganized and demoralized army and an angry population. These conditions led to a revolt in the army which eventually spiraled into the ongoing Somali Civil War.

Somalia, officially the Federal Republic of Somalia (Somali: Jamhuuriyadda Federaalka Soomaaliya; Arabic: جمهورية الصومال الفيدرالية), is a country in the Horn of Africa. The country is bordered by Ethiopia to the west, Djibouti to the northwest, the Gulf of Aden to the north, the Indian Ocean to the east, and Kenya to the southwest. Somalia has the longest coastline on Africa's mainland. Its terrain consists mainly of plateaus, plains, and highlands. Hot conditions prevail year-round, with periodic monsoon winds and irregular rainfall. Somalia has an estimated population of around 15 million, of which over 2 million live in the capital and largest city Mogadishu, and has been described as Africa's most culturally homogeneous country. Around 85% of its residents are ethnic Somalis, who have historically inhabited the country's north. Ethnic minorities are largely concentrated in the south. The official languages of Somalia are Somali and Arabic. Most people in the country are Muslims, the majority of them Sunni.In antiquity, Somalia was an important commercial center. It is among the most probable locations of the fabled ancient Land of Punt. During the Middle Ages, several powerful Somali empires dominated the regional trade, including the Ajuran Sultanate, the Adal Sultanate, and the Sultanate of the Geledi.

In the late 19th century, Somali Sultanates like the Isaaq Sultanate and the Majeerteen Sultanate were colonized by Italy, Britain and Ethiopia. European colonists merged the tribal territories into two colonies, which were Italian Somaliland and the British Somaliland Protectorate. Meanwhile, in the interior, the Dervishes lead by Mohammed Abdullah Hassan engaged in a two-decade confrontation against Abyssinia, Italian Somaliland, and British Somaliland and were finally defeated in the 1920 Somaliland Campaign. Italy acquired full control of the northeastern, central, and southern parts of the area after successfully waging the Campaign of the Sultanates against the ruling Majeerteen Sultanate and Sultanate of Hobyo. In 1960, the two territories united to form the independent Somali Republic under a civilian government.The Supreme Revolutionary Council seized power in 1969 and established the Somali Democratic Republic, brutally attempting to squash the Somaliland War of Independence in the north of the country. The SRC subsequently collapsed 22 years later, in 1991, with the onset of the Somali Civil War and Somaliland soon declared independence. Somaliland still controls the northwestern portion of Somalia representing just over 27% of its territory. Since this period most regions returned to customary and religious law. In the early 2000s, a number of interim federal administrations were created. The Transitional National Government (TNG) was established in 2000, followed by the formation of the Transitional Federal Government (TFG) in 2004, which reestablished the Somali Armed Forces. In 2006, with a US backed Ethiopian intervention, the TFG assumed control of most of the nation's southern conflict zones from the newly formed Islamic Courts Union (ICU). The ICU subsequently splintered into more radical groups, such as Al-Shabaab, which battled the TFG and its AMISOM allies for control of the region.By mid-2012, the insurgents had lost most of the territory they had seized, and a search for more permanent democratic institutions began. Despite this, insurgents still control much of central and southern Somalia, and wield influence in government-controlled areas, with the town of Jilib acting as the insurgents' de-facto capital. A new provisional constitution was passed in August 2012, reforming Somalia as a federation. The same month, the Federal Government of Somalia was formed and a period of reconstruction began in Mogadishu. Somalia has maintained an informal economy mainly based on livestock, remittances from Somalis working abroad, and telecommunications. It is a member of the United Nations, the Arab League, African Union, Non-Aligned Movement, and the Organisation of Islamic Cooperation.