“One thing has struck me as a bit queer. During my two terms of office the whole Democratic press, and the morbidly honest and 'reformatory' portion of the Republican press, thought it horrible to keep U. S. troops stationed in the Southern States, and when they were called upon to protect the lives of negroes– as much citizens under the Constitution as if their skins were white– the country was scarcely large enough to hold the sound of indignation belched forth by them for some years. Now, however, there is no hesitation about exhausting the whole power of the government to suppress a strike on the slightest intimation that danger threatens. All parties agree that this is right, and so do I. If a negro insurrection should arise in South Carolina, Mississippi, or Louisiana, or if the negroes in either of these states, where they are in a large majority, should intimidate the whites from going to the polls, or from exercising any of the rights of American citizens, there would be no division of sentiment as to the duty of the president. It does seem the rule should work both ways.”

Regarding keeping U.S. Army soldiers stationed in southern U.S. states to protect the safety and civil rights of freed slaves (26 August 1877), as quoted in The Papers of Ulysses S. Grant: November 1, 1876-September 30, 1878, by U.S. Grant, pp. 251-252.
1870s, Letter to Daniel Ammen (1877)