Answer:
On the British side fighting against the Germans and Later on Russia joins the allies.
Explanation: Germany and the others were apart of the Central powers because they were in the center of Europe. Also the United States joined the war because Germany sent a message to Mexico to attack the United States but Mexico declined and told the U.S about it, and after Germany had sunk their ships heading to Britain with some passengers the U.s was furious and decided to join in.