Longest Wars of the 20th Century

• The Vietnam War (1955–1975)
  20 years
• The Chinese Civil War (1927–1950)
  23 years
• The Soviet–Afghan War (1979–1989)
  10 years
The Algerian War of Independence (1954–1962)
8 years
• The Iran–Iraq War (1980–1988)
Guatemalan Civil War — 1960–1996
36 years