Question

Why did the u.s. senate reject the treaty of versailles?

Answer 1

It's mainly because of Article X of the Treaty, which required members of the League of Nations to come to the aid of other nations in the League when they were attacked.

Many senators, led by Henry Cabot Lodge (chair of the Senate Foreign Relations Committee), worried that this provision of the treaty would drag the United States into unnecessary foreign conflict and thus impede on America's freedom of action. Hence, they wanted to ratify the treaty with "reservations" (known as the Lodge Reservations) stating the United States would not be obligated to intervene should a member nation of the League of Nations be attacked. There was also a faction of U.S. senators called the "incorrigibles", who wouldn't accept the treaty under any circumstances.

Woodrow Wilson had essentially given up all of his famous "Fourteen Points" at the bargaining table at Versailles with the exception of the creation of a League of Nations. Therefore, he refused to compromise. It didn't help that just as Wilson was about to go on a huge speaking tour across the country in favor of the treaty, he had a crippling stroke. So the Lodge faction and the incorrigibles formed a big enough voting bloc to ensure the defeat of the treaty in the Senate.

Answer 2

Answer: The Senate worried about the US being pulled into future wars that were not directly related to US national security.

Context/detail:

The United States never joined the League of Nations, in spite of the fact that an organization such as the League of Nations was the signature idea of US President Woodrow Wilson. He had laid out 14 Points for establishing and maintaining world peace following the Great War (World War I). Point #14 was the establishment of an international peacekeeping association. The Treaty of Versailles adopted that idea, but back home in the United States, there was not support for involving America in any association that could diminish US sovereignty over its own affairs or involve the US again in wars beyond those pertinent to the United States' own national security. Because of its objections to membership in the League of Nations, the United States Senate refused to ratify the Treaty of Versailles.