in five wars. Those five official wars include the Revolutionary War, the Civil War, World War I, World War II, and the Vietnam War. The War of 1812, Korean War, Cold War, Gulf War, Iraq War, and the current wars in the Middle East are not included in this list because war was never officially declared by the US.
The Revoultionary War was fought for the United State's independence from Britian in the 1700's. The war began on April 19, 1775, and ended July 4, 1776, upon signing of the Declaration of Independence.
The Civil War was fought to keep the United States one country when the Southern Confederates attempted to secede. This war began in January 1861 and ended February 1865.
World War I was fought against the Central Powers, which included Germany, Austria-Hungary, the Ottoman Empire, and Bulgaria. The Allied forces included the United States, Japan, Russia, Britian, France, Italy, Serbia, and Romania. The war began on June 28, 1914, and ended on June 28, 1919, with the signing of the Treaty of Versailles.
World War II was fought against the Nazi-German empire and the Japanese empire, both of which were directly fighting the United States and US Allies. The war began on September 1, 1939, and ended on September 2, 1945.
The Vietnam War was fought to keep Allied South Vietnam from being overtaken by Communist North Vietnam, supported by Communist China and Communist Soviet Russia. The war began in March of 1959 and ended in August 1974.