A civil war is a war between organized groups within the same nation state or republic, or, less commonly, between two countries created from a formerly united nation state. The aim of one side may be to take control of the country or a region, to achieve independence for a region, or to change government policies. The term is a calque of the Latin bellum civile which was used to refer to the various civil wars of the Roman Republic in the 1st century BC.

A civil war is a high-intensity conflict, often involving regular armed forces, that is sustained, organized and large-scale. Civil wars may result in large numbers of casualties and the consumption of significant resources.

Civil wars since the end of World War II have lasted on average just over four years, a dramatic rise from the one-and-a-half year average of the 1900-1944 period. While the rate of emergence of new civil wars has been relatively steady since the mid-19th century, the increasing length of those wars resulted in increasing numbers of wars ongoing at any one time. For example, there were no more than five civil wars underway simultaneously in the first half of the 20th century, while over 20 concurrent civil wars were occurring at the end of the Cold War, before a significant decrease as conflicts strongly associated with the superpower rivalry came to an end. Since 1945, civil wars have resulted in the deaths of over 25 million people, as well as the forced displacement of millions more. Civil wars have further resulted in economic collapse; Burma (Myanmar), Uganda and Angola are examples of nations that were considered to have promising futures before being engulfed in civil wars.

The Mozambican Civil War began in 1977, two years after the end of the war of independence. The ruling party, Front for Liberation of Mozambique (FRELIMO) and the national armed forces FAM (Armed Forces of Mozambique), was violently opposed from 1977 by the Rhodesian- and (later) South African-funded Mozambique Resistance Movement (RENAMO). About 1 000 000 people died in fighting and from starvation, five million civilians were displaced, many were made amputees by landmines, a legacy from the war that continues to plague Mozambique. Fighting ended in 1992 and the country's first multi-party elections were held in 1994.

Mozambican resistance began to surface, as some groups within the Mozambican society eventually started to blame the Portuguese authorities for centuries of exploitation, oppression and neglect.^{[citation needed]} After a successful wave of independence movements in other African territories, cold war powers and the international community started to suggest that Portugal should leave its territories in Africa. Sentiment for Mozambique's own national independence developed and on 25 June 1962 several Mozambican anti-Portuguese political groups formed the Mozambique Liberation Front (FRELIMO) in Dar-es-Salaam, Tanzania.