
Jackie Robinson was an exceptionally talented baseball player. In fact, such was his talent that in 1947 he obliterated an unwritten policy within baseball that had, until this point, prevented players of African descent from joining teams in either the minor or major leagues. After his baseball career ended, Robsinson took an active role in the political world and fought, amongst other things, racial segregation. He sent the following powerful letter to President Eisenhower in 1958. Eisenhower's reply can be read here.
(As an aside, for those wondering: Jackie Robinson was Vice President of the Chock full o' Nuts company from 1957 onwards, hence the letterhead.)
Transcript follows. Image of letter courtesy of the National Archives; Image above, of Jackie Robinson, courtesy of Collider.

Image: National Archives
Transcript
May 13, 1958
The President
The White House
Washington, D.C.
My dear Mr. President:
I was sitting in the audience at the Summit Meeting of Negro Leaders yesterday when you said we must have patience. On hearing you say this, I felt like standing up and saying, 'Oh no! Not again.'
I respectfully remind you sir, that we have been the most patient of all people. When you said we must have self-respect, I wondered how we could have self-respect and remain patient considering the treatment accorded us through the years.
17 million Negroes cannot do as you suggest and wait for the hearts of men to change. We want to enjoy now the rights that we feel we are entitled to as Americans. This we cannot do unless we pursue aggressively goals which all other Americans achieved over 150 years ago.
As the chief executive of our nation, I respectfully suggest that you unwittingly crush the spirit of freedom in Negroes by constantly urging forbearance and give hope to those pro-segregation leaders like Governor Faubus who would take from us even those freedoms we now enjoy. Your own experience with Governor Faubus is proof enough that forbearance and not eventual integration is the goal the pro-segregation leaders seek.
In my view, an unequivocal statement backed up by action such as you demonstrated you could take last fall in dealing with Governor Faubus if it became necessary, would let it be known that America is determined to provide—in the near future—for Negroes—the freedoms we are entitled to under the constitution.
Respectfully yours,
(Signed)
Jackie Robinson