Why did the US fail to ratify the Treaty of Versailles?
When contemplating the reason(s) for the failure of the United States to ratify the Treaty of Versailles, appended to which was The Covenant of the League of Nations, one needs to keep in mind the provision of the United States Constitution pertaining to international treaties. The authors of the constitution were very concerned about establishing a form of government that would be exceedingly unlikely to devolve into a dictatorship. The key to such a governmental structure would be one built around the concept of a balance of power among the three main branches the Constitution would establish. The importance to the authors of the constitution of the Legislative Branch, that, by design, would be closest and most responsive to the public, was evident in its placement within the text of the Constitution, in effect, the opening article. Article II of the Constitution, then, established the Executive Branch, to be led by a president. It is within Article II that we begin to understand the reason for the U.S. rejection of membership in the League of Nations. Section II of this article vests responsibility for the negotiation of treaties with the Executive Branch, but it gives to the U.S. Senate the authority to accept or reject such agreements. The precise text of this constitutional provision follows:
Article II, Section II
"He (the president) shall have Power, by and with the Advice and Consent of the Senate, to make Treaties, provided two thirds of the Senators present concur; and he shall nominate, and by and with the Advice and Consent of the Senate, shall appoint Ambassadors, other public Ministers and Consuls . . ." [Emphasis added]
This background on the separation of powers within the federal government is essential for understanding the fate of the League of Nations. Had President Woodrow Wilson, whose Fourteen Points intended to establish a new international structure or framework to prevent future conflicts like that which precipitated the Treaty of Versaille, had sole authority for deciding into what kinds of agreements the United States would enter with other nations, then the United States would have been a founding member of the organization he, President Wilson, envisioned. Because of the constitutional authorities of the Legislative Branch of government, however, Wilson was not the sole determinant of such relationships. And, to the president's chagrin, one of the most powerful members of the Senate, Henry Cabot Lodge, a staunch political foe who philosophically opposed Wilson's vision of collective security, opposed it as did other Senate Republicans.
To appreciate the reason Republicans opposed U.S. participation in the League of Nations, let's look at the most operative provisions of the Covenant:
"The Members of the League undertake to respect and preserve as against external aggression the territorial integrity and existing political independence of all Members of the League. In case of any such aggression or in case of any threat or danger of such aggression the Council shall advise upon the means by which this obligation shall be fulfilled." [Article X]
"Any war or threat of war, whether immediately affecting any of the Members of the League or not, is hereby declared a matter of concern to the whole League, and the League shall take any action that may be deemed wise and effectual to safeguard the peace of nations." [Article XI]
This declaration of intent binding the League's members to a collective security arrangement was anathema to the isolationist principles held by many Republicans, who feared an unending commitment to intervene in Europe's seemingly unending propensity for war. So, we have a Senate leader, Lodge, who both intensely dislikes the president and a political party that just as intensely dislikes the notion of formal commitments to diplomatic disputes and military affairs on the other side of the Atlantic. And, isolationism wasn't the only obstacle within the United States to membership in the League of Nations. Unlike European nations, the United States was an amalgamation of many of those overseas countries, constituted as it was by successive flows of immigrants. Consequently, competing and parallel agendas among American ethnic groups, like Italian Americans, Irish Americans, German Americans, and so forth, each of which had its own ideas or objections, helped to derail U.S. ratification of the Treaty of Versailles, including the Covenant of the League of Nations. In short, ratification of this highly contentious treaty was a 'bridge too far' for an increasingly frail and weakened president.
While it is important to look at the Fourteen Points when considering the reason behind why the US failed to ratify the Treaty of Versailles, we must also take into consideration US public opinion on WWI.
Before we entered WWI in 1917, Wilson and a majority of the American public favored isolationism, which meant staying out of affairs that did not directly impact the United States. When we entered the war, the sentiment against going in to war remained. It seemed to many people in America that the US had entered a European war and lost a lot of American men.
When Wilson presented his 14 points, the last point called for the League of Nations, a precursor to the United Nations that would hopefully prevent future conflicts at such a large, global scale. The US Senate, however, was not as optimistic. Wilson argued that the League of Nations was the future of global collective security, and that the US should take a more active role in world interests. The Senate did not agree; senators like Henry Cabot Lodge rejected the premise of the League of Nations, favoring the original isolationist policy that had kept America out of what he considered to be a European war. Additionally, Lodge and other Senators voted on partisan lines, wanting to undermine Wilson's League of Nations to secure Republican dominance in US politics. Ultimately, Wilson's failing health made it impossible to campaign in favor of the League of Nations, and the Treaty of Versailles was ultimately rejected in the Senate.
To recap, the main reasons behind the Senate's failure to sign the Treaty was because of strong isolationist sentiments and the desire to stay out of foreign affairs (which the League of Nations would not allow the US to do). Had the Treaty of Versailles been signed by the US, and the US joined the League of Nations, the US would have expected to play a more active role in global politics. Regardless, the United States did become a major world power and interventionist nation in the decades to come.
The main reason why the US Senate did not ratify the Treaty of Versailles was the League of Nations. There were serious concerns that the League would erode US sovereignty and pull the US into further wars that were not in its interest.
Many Americans were worried about the collective security provisions in the League of Nations charter. They felt that the US might be forced to go to war in order to protect other nations that were invaded. This could happen, they felt, regardless of whether those wars were important to US interests. For this reason, they felt that the League of Nations would reduce America’s ability to control its own foreign policy and would potentially involve the country in unnecessary wars.