What Is American Expeditionary Force in History?

The American Expeditionary Force (AEF) was a military organization formed by the United States to fight in World War I. The AEF was created in 1917 after the United States declared war on Germany. It was led by General John J. Pershing and made up of over two million American soldiers.


Before the United States entered World War I, President Woodrow Wilson had tried to keep the country neutral. However, when Germany began using submarines to sink American ships, Wilson asked Congress for a declaration of war. In April 1917, the United States officially entered World War I.

Formation of the AEF

After declaring war on Germany, it became clear that the United States needed to form an army to fight in Europe. General John J. Pershing was appointed as commander of the AEF and began organizing troops for deployment.

The first American troops arrived in France in June 1917. However, it took several months for the AEF to become fully operational. By September 1918, over two million American soldiers were fighting on the Western Front.

Role in World War I

The AEF played a significant role in helping to turn the tide of World War I in favor of the Allied Powers. The arrival of fresh American troops helped to bolster morale among Allied soldiers and weakened German resistance.

One of the most significant battles fought by the AEF was at Meuse-Argonne in September 1918. This battle lasted for 47 days and resulted in over 120,000 American casualties. Despite heavy losses, however, the AEF emerged victorious and helped hasten an end to World War I.


The formation and success of the AEF had a profound impact on American military history. It showed that America could field a formidable army and play a significant role in global conflicts.

The AEF also helped to cement the United States’ position as one of the world’s superpowers. It paved the way for America’s involvement in World War II and its continued military presence around the world.


The American Expeditionary Force was a crucial part of World War I history. It demonstrated America’s ability to field a strong military force and played a significant role in helping to end the war. The legacy of the AEF continues to be felt today, as America remains a major player in global military affairs.