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The Length of American Wars: Comparing America’s Wars by Duration in Months

Comparing America’s Wars by Duration in Months

The Length of American Wars

Below is a look at America’s major wars and their length in months. Time periods are rounded up or down for ease of comparison. American wars have occurred frequently since the birth of the United States during the American Revolutionary War.


The longest wars are listed first in descending order by length. The start dates reflect when the United States entered the wars.


*NOTE: This list highlights what are considered America’s MAJOR wars and conflicts. Many of the smaller, less well-known conflicts were quite long, for instance, the U.S. military occupation of Haiti, from 1915 – 1934, lasted 19 years.

War in AfghanistanOctober, 2001 to 2021 = 238 months (19.8 years) *NOTE: The War in Afghanistan, begun soon after the September 11 terror attacks, is currently America’s longest major conflict.


Vietnam War–August, 1964 to April, 1975= 116 months (9.6 years) [American involvement began in the late 1950s, but major U.S. combat forces began taking part in large unit combat in 1964]

Iraq War–March, 2003 to 2011 = 105 months (8.75 years)

American Revolution–April, 1775 to September, 1783= 100 months (8.33 years)

U.S. Civil War–April, 1861 to April, 1865= 48 months (4 years)

World War II–December, 1941 to September, 1945= 45 months (3.75 years)

Korean War-June, 1950 to July, 1953= 37 months (3.08 years)

War of 1812–June, 1812 to February, 1815= 32 months (2.6 years)

U.S.-Mexican War– May, 1846 to February, 1848= 21 months (1.75 years)

World War I–April, 1917 to November, 1918= 19 months (1.6 years)


Spanish-American War–April, 1898 to August, 1898= 5 months (0.4 years)

Gulf WarJanuary, 1991 to March, 1991= 3 months (0.25 years)

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