Final answer:
Henry Cabot Lodge was skeptical of the Treaty of Versailles and the League of Nations, fearing U.S. military commitments without Congressional approval and a loss of sovereignty, leading to the U.S not joining the League.
Step-by-step explanation:
Henry Cabot Lodge, the Republican leader of the Senate, was very suspicious of the Treaty of Versailles, specifically with regards to the United States joining the League of Nations. Lodge and other Republicans feared that Article X of the treaty would commit the U.S. to international military involvement without the constitutional consent of Congress, potentially drawing the nation into foreign disputes.
Lodge was an isolationist who, along with others, wanted to avoid such entanglements, and suspected that it might infringe on U.S. sovereignty. This opposition led to the U.S. Senate not approving the treaty, rendering the United States absent from the League of Nations. This absence significantly weakened the League's international authority and ability to resolve disputes.
The contentious political environment surrounding the treaty culminated in a separate peace treaty with Germany, the Knox-Porter Resolution, formalizing the end of war between the two nations in 1921.