During world war one, the united states, russia, great britain, and france were a part of the allies, who were they fighting?

Allies fought against the Central Powers - Germany, Austria-Hungary, Bulgaria and the Ottoman Empire.

Explanation:

The Allies (Entente Powers) were the coalition that fought against the Central Powers of Germany, Austria-Hungary, the Ottoman Empire and Bulgaria from 1914 to 1918.

During his visit in Sarajevo, Bosnia, Franz Ferdinand (the heir to the throne of Austria-Hungary), was killed by a Serbian. As a result, Austria-Hungary declared war on Serbia. Russia had an alliance with Serbia, and therefore got involved. In addition, Germany, having an alliance with Austria-Hungary, declared war on Russia. Britain entered the war because of Germany's invasion of Belgium. The Ottoman Empire joined the war in August 1914, upon signing the Turco-German Alliance. Bulgaria declared war on Serbia in October 1915.