On 7 December, 1900, Mark Twain introduced Winston Churchill at the Waldorf-Astoria, Zwick places this on December 12th:
“... I think that England sinned when she got herself into a war in South Africa which she could have avoided, just as we have sinned in getting into a similar war in the Philippines. Mr. Churchill by his father is an Englishman; by his mother he is an American; no doubt a blend that makes the perfect man. England and America; yes, we are kin. And now that we are also kin in sin, there is nothing more to be desired. The harmony is complete, the blend is perfect — like Mr. Churchill himself, whom I now have the honor to present to you”

(“Mark Twain as Missionary,” Boston Transcript, 14 December 1900, p.9.) (S&G pages 723-4)

Zwick notes that Churchill “… to his first American audience at the Waldorf Astoria in New York City. ... Churchill supported British Imperialism and his reception in New York was boycotted by many American anti-imperialists. Twain agreed to introduce Churchill but delivered a scathing indictment of imperialism in the process. Before concluding that England and America were “kin in sin” for their respective wars in South Africa and the Philippines, he noted how they were also united when they “both stood timorously by at Port Arthur and wept sweetly and sympathizingly and shone while France and Germany helped Russia to rob the Japanese.” (pages 96-7)

... at the end of the year and the end of the century, Clemens wrote a sardonic “greeting”: “A salutation-speech from the Nineteenth Century to the ‘Twentieth, taken down in short-hand by Mark Twain: I bring you the stately matron named Christendom, returning bedraggled, besmirched and dishonored from pirate-raids in Kiao-Chou, Manchuria, South Africa & the Philippines, with her soul full of meanness, her pocket full of boodle and her mouth full of pious hypocrisies. Give her soap and a towel, but hide the looking-glass” (“New Century Greeting Which Mark Twain Recalled,” New York Herald, 30 December 1900, Section I, p. 7). (Smith & Gibson, V2 page 726) 

Zwick (page 159) writes: In just two sentences he blasted four prominent manifestations of the imperial surge that was taking place worldwide at the end of the nineteenth century: Germany’ s seizure of Kiao Chow Bay in China, Russia’s occupation of Manchuria, the Boer War in South Africa, and the Philippine-American War.

 Zwick, on page 114, provides a facsimile of the greeting with a final note: “Give her the glass: it may from error free her / When she shall see herself as others see her. 

Two weeks later Mark Twain agreed to serve as a vice president of the Anti-Imperialist League of New York. 

At the beginning of 1901, in the February North American Review, Mark Twain’s wrath against the recent policies of the Czar in China, of Kaiser Wilhelm and Foreign Secretary Joseph Chamberlain in South Africa, and of President McKinley in the Philippines boiled over again in “To the Person Sitting in Darkness — one of the most powerful pieces of invective he ever wrote. Page 726