Who were the anti-imperialists during the U.S. expansionist period?

The anti-imperialists during the U.S. expansionist period were characterized by their opposition to the annexation of territories and the broader concept of U.S. expansionism. This group raised concerns about several issues, including the moral implications of imperialism, the impact on American values of democracy and self-determination, and the potential consequences of ruling over distant territories and populations without their consent. Prominent figures in the anti-imperialist movement, such as Mark Twain and Andrew Carnegie, argued that expansionism contradicted the core tenets of American democracy, particularly in terms of respecting the autonomy and rights of other nations. They feared that imperialism would lead to the United States losing its principles and becoming more like the empires it had historically opposed.