King was among those arrested in Birmingham during a non-violent protest. Enduring the poor conditions of the jail, he wrote a letter in response to “A Call For Unity,” written by clergy members that day of his arrest.

Writing on the newspaper with the article, and on other scraps of paper given to him by trusted staff, he wrote his famous article, dated April 16, 1963. It was known as “Letter From The Birmingham (City) Jail.” That document was later polished and re-printed several times as well as being included in other publications. It is regarded as King’s classic argument for civil disobedience.