The Laotian Civil War (1953–75) was a fight between the Communist Pathet Lao, often North Vietnamese of Lao ancestry, and the Royal Lao Government in which both the political rightists and leftists received heavy external support for a proxy war from the global Cold War superpowers. Among United States Central Intelligence Agency Special Activities Division US and Hmong veterans of the conflict, it is known as the Secret War.

The Kingdom of Laos was a covert theatre for battle for the other belligerents during the Vietnam War. The Franco–Lao Treaty of Amity and Association signed 22 October 1953, transferred remaining French powers – except control of military affairs – to the Royal Lao Government – which did not include any representatives from the Lao Issara anti-colonial armed nationalist movement — and otherwise establishing Laos as an independent member of the French Union. The following years were marked by a rivalry between the neutralists under Prince Souvanna Phouma, the right wing under Prince Boun Oum of Champassak, and the left-wing Lao Patriotic Front under Prince Souphanouvong and future Prime Minister Kaysone Phomvihane. A number of attempts were made to establish coalition governments, and a "tri-coalition" government was finally seated in Vientiane.

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.