Short answers, pulled from the story.
Civil wars since the end of World War II have resulted in more than 25 million deaths, as well as the forced displacement of millions of additional people. Countries including Somalia, Burma (Myanmar), Uganda, and Angola are cited as nations that had promising economic futures before being engulfed in civil conflicts.
The Collier-Hoeffler Model is a framework developed by a World Bank team that examined 78 five-year periods of civil war between 1960 and 1999. It found that a country at "peak danger", with primary commodity exports comprising 32% of GDP, faced a 22% risk of civil war in any five-year window, compared to just 1% for a country with no primary commodity exports. The model identified economic opportunity costs, diaspora funding, and state weakness as stronger predictors of civil war than ethnic or religious identity.
International intervention dramatically extends civil war duration. On average, a civil war with any international intervention lasts 300% longer than one without. When both sides receive outside support, wars are longer by an additional 92%, and superpower involvement adds a further 72%. In a conflict like the Angolan Civil War, which saw two-sided intervention including by two superpowers, wars would be 538% longer on average than unintervened conflicts.
The average duration of civil wars rose from one and a half years in the 1900-1944 period to just over four years after 1945. Ann Hironaka attributes this to the proliferation of weak post-colonial states, routine foreign intervention on both sides, and Cold War rivalry that kept conflicts alive. The number of ex-colonial states jumped from roughly 30 to almost 120 after World War II, and Hironaka's analysis estimates this increase raised the incidence of civil wars by 165% over pre-1945 levels.
High dependence on primary commodity exports is one of the strongest predictors of civil war risk identified by the Collier-Hoeffler Model. A country with commodities comprising 32% of GDP faces a 22% chance of civil war in any five-year period, while a country with no primary commodity exports faces only a 1% chance. Researchers explain this as reflecting how easily gold mines and oil fields can be captured and controlled compared to other forms of economic activity.
The fall of the Berlin Wall in 1989 corresponded with a 92% reduction in the duration of Cold War-associated civil wars, equivalent to roughly a tenfold increase in the rate of their resolution. Long-running Cold War-linked conflicts in Guatemala (1960-1996), El Salvador (1979-1991), and Nicaragua (1970-1990) all reached their conclusions around that period. Civil wars involving pro- or anti-communist forces had lasted 141% longer on average than non-Cold War conflicts.