Postcard showing the Plymouth Church in ca. 1905. Many celebrated Americans came to the Plymouth Church. For example Abraham Lincoln spoke at Plymouth Church or Dr. Martin Luther King, Jr. preached a sermon on "The American Dream. In addition many other famous writers and activists, including Mark Twain, Clara Barton, Charles Dickens, Ralph Waldo Emerson, Horace Greeley, and William Thackery spoke at Plymouth. Under the leadership of its first minister, Henry Ward Beecher, it became the foremost center of anti-slavery sentiment in the mid-19th century.