World War One brought devastation and destruction on a scale which had never been witnessed before, with lives lost on an almost unimaginable scale. The League of Nations was set up with the aim of preventing anything like that happening again, but failed because of a number of simple reasons.
As the effects of the First World War began to die down, the US adopted a policy of isolation from European affairs. Despite Woodrow Wilson having come up with the idea of the League of Nations, he didn't want his country to be involved with daily European political life.
The result was that the League would have to function for the rest of its life without the active support of one of the world's major powers.
The constitution of the League didn't ask for nations to provide an army for a military force, which was the League's last means of restoring order or standing up to an aggressive nation.
Without military power as a buffer, the League was seriously weakened because no smaller country could be protected against a larger country if they were invaded or threatened and there was ultimately no deterrent.
Under the terms of the Versailles Treaty, Germany wasn't allowed to join the League. This meant that Germany felt excluded and the League was weakened because one nation who could've made a positive contribution, in terms of a military force at least, was not allowed to.
Russia was also excluded from the League of Nations because it became a communist country towards the end of the war and communism was beginning to cause as much fear in Europe as fascism would less than two decades later.
The result was that, with America not involved as well, the League of Nations was missing three of the most powerful countries in the world.
BRITAIN AND FRANCE
Two of the world's remaining strengths, Britain and France, were in the League but weren't particularly actively involved. Both were preoccupied with rebuilding after the Great War and although France frequently spoke out about certain issues, they were reluctant to do anything without British support.
Their failure to get involved in anything outside Western European affairs meant that the League ended up as a sterile talking shop.
THE LEAGUE AND WAR
Article 11 of the League's Covenant stated: "Any war or threat of war is a matter of concern to the whole League and the League shall take action that may safe guard peace." Therefore, any conflict between nations which ended in war and the victor of one over the other must be considered a League failure.
The League failed to deal with many disputes adequately and in some cases, like the dispute between Italy and Albania in 1923, favoured larger nations over smaller nations. In fact, when France invaded the Ruhr in the same year, the League showed that its member states could even break their own rules.
The League of Nations failed to maintain peace for many reasons and these were unfortunately built into the formation of the League from the start. With three major powers missing and no military support it was inevitable it would be unable to stop war if the tensions continued.