“The absence of the United States was the most important reason for the failure of the League of Nations in the 1930s”. How far do you agree with this statement?

The League of Nations was ultimately ineffective in its goal of promoting cooperation and maintaining global peace, and a key reason for its failure was the fact that the United States never joined. Although the League had been the brainchild of American President Woodrow Wilson, who had proposed an international collaborative body as a part of his Fourteen Points, American public opinion soon turned against the idea of joining the League. A number of isolationist Republican Presidents were elected in the 1920s due to their message that the United States would not become involved in the affairs of other nations, and that American troops would not again die on foreign soil, as they had in the First World War. American absence defanged the League, making it unable to effectively enforce its decisions, as without America’s military presence the League lost the ability to create a formidable standing army, and so none was established. Additionally, the League’s ability to impose economic sanctions on countries was also severely restricted by the fact that any nation that the League placed sanctions on remained free to trade with the United States, which was the world’s largest economy. Therefore, it can be said that the absence of the USA severely hurt the League’s ability to enforce its decisions, dramatically reducing the League’s global authority and therefore its effectiveness in preserving peace. 
Another reason for the failure of the League was the reluctance of key members such as Britain and France to act in the best interest of the League rather than themselves. Already weakened by the absence of the United States, the League required absolute commitment from the global powers who were members, however Great Britain and France proved themselves unwilling to make any sacrifice in order to protect peace, as shown by their refusal to intervene following China’s invasion of Manchuria in 1931 and Germany’s remilitarisation of the Rhineland in 1936. The two nations took a non-interventionist path for different reasons, as while France was still reeling from enormous losses caused by the First World War, pacifist public opinion had been steadily rising in Britain, resulting in the refusal to confront foreign nations who had acted aggressively. Therefore, it is clear that the self interest of France and Britain showed that key members were not willing to protect the principles of the League, dooming it to fail. The League had been relatively successful amidst the economic prosperity of the 1920s, showing that many of the underlying problems with the League were exacerbated by the Wall Street Crash in 1929 and subsequent Great Depression. Major economic downturn in Germany and Japan created great political instability, leading to the rise of militaristic fascist governments in both nations, led by Adolf Hitler and Hideki Tojo, which sought to expand their nations and restore pride at the cost of peace. The aggressive actions of Japan, Italy and Germany exposed the self interest of Britain and France, while also exploiting many structural weaknesses of the League, such as the fact that all votes had to be unanimous, giving each state effective veto power. Therefore it is clear that the Great Depression caused a wave of aggressive leaders to come to power, who in turn exposed a number of weaknesses of the League. 
Overall, it is clear that while the League of Nations was significantly weakened by the absence of the United States, as well as the self interest of leading members and structural weaknesses, however these issues were only exposed and exploited by the actions of militaristic leaders who came to power as a result of the Great Depression, revealing economic downturn to be the most significant reason for the failure of the League of Nations in the 1930s.