As Memorial Day unfolds and fallen U.S. soldiers are remembered it's an opportune time to look back at the nation's top military leaders at times of great crisis for the nation.

Unsurprisingly, the nation's founding, its biggest civil conflict, and a major international conflict in the 20th century have produced some of the most recognizable names.

REVOLUTIONARY WAR - GEORGE WASHINGTON

George Washington, who was later to become the first president of the United States, served as Commander-in-Chief of the Continental Army from 1775 to 1787. During that time, he led the colonists to victory over Britain.

In between the Revolutionary War and the next overarching conflict, the American Civil War, the U.S.  overcame various relatively smaller foreign challenges. The U.S. thwarted British attempts to retake it in the War of 1812 and successfully expanded westward by asserting control over land from Mexico and Britain. During that time, the U.S. fought and relocated the indigenous people of the areas as part of the Manifest Destiny belief by expansionists who saw the U.S. destined to seize control of the territory from the Atlantic to the Pacific Oceans.

AMERICAN CIVIL WAR - ULYSSES S. GRANT

The top military leader during the U.S. Civil War, which lasted from 1861 to 1865 was Gen. Ulysses S. Grant, head of the Union Army, who ultimately forced the surrender of Robert E. Lee, the top general in the Confederate States of America. Grant would eventually become U.S. President in 1869. Lee had the opportunity to be a leader in the Union Army to put down a rebellion. However Lee refused, resigned and became the head of the Army of North Virginia, one of the main Confederate armies.

WORLD WAR I - JOHN JOSEPH PERSHING

The 20th century saw two of the largest global conflicts ever, with World War II and World War I, formerly known as the Great War.

U.S. Participation came in near the end of the war and full participation did not begin until the last year, 1918. Gen. Joseph Pershing led U.S. troops at the time to help allies Russia, Britain, France and Italy ward off a German-led takeover of Europe.

WORLD WAR II - DWIGHT EISENHOWER, DOUGLAS MACARTHUR

U.S. Generals also emerged during World War II, which took place both in Europe, Africa, the Pacific Ocean and Asia. It lasted from 1939 until 1945, with U.S. entry coming in 1941 after the Japanese attack on Pearl Harbor and Germany's declaration of war against the United States shortly thereafter.

Among the noteworthy leaders were Gen. Dwight Eisenhower, who served as General of the Army during that conflict, and later was elected as U.S. President.

Meanwhile on the other side of the world Gen. Douglas MacArthur was ranked as high as Supreme Commander of the Allied Powers in Japan as the United States sought to rebuild the country following the war, effectively leading the country from 1945 until 1948.