How and why did the Allies win World War I?
When we think about why the Allies won World War I, we can point to the Allies' superior manpower and resources, the British blockade against the Germans, the entry of the United States into the war, and the Russian Revolution. Let's look at each of these to get you started on this assignment.
The Germans made a big mistake at the beginning of World War I in assuming that they would achieve a quick and easy victory. The Germans neglected agricultural production to put as many men into the war as possible, but when the war dragged on and bogged down in the trenches, Germany and its allies were left short of food. Hunger greatly affected public support of the war effort. The Allies, on the other hand, kept up agricultural production, and the U.S. and Canada were able to supply sufficient food to the armies. The Allies could also claim superior manpower as well as more stable economies and access to greater resources with regard to weapons and equipment.
The British blockade of Germany tightened up supplies even further as Germany could not import the resources it needed. Again, people who are hungry do not enthusiastically support a war, and hungry soldiers do not fight as efficiently.
The entry of the U.S. into the war also made a huge difference for the Allies. When the Germans started bombing U.S. ships, Americans turned against Germany in a major way. When the U.S. entered the war, it brought new troops and plenty of resources with it to replenish the Allied war effort.
Finally, the Russian Revolution created a huge problem for Germany and its allies. When the Communists took over Russia, their counterparts in Germany tried to do the same there, weakening Germany even more. This instability helped break the German war effort in the end.