Impeachment before Twitter

Since Twitter wasn't around in 1868, the President's congressional opponents could not impeach him for tweeting. But they did their best:
Articles of Impeachment

ARTICLE 1.

[...]

ARTICLE 10.That said Andrew Johnson, President of the United States, unmindful of the high duties of his high office and the dignity and proprieties thereof, and of the harmony and courtesies which ought to exist and be maintained between the executive and legislative branches of the Government of the United States, designing and intending to set aside the rightful authorities and powers of Congress, did attempt to bring into disgrace, ridicule, hatred, contempt and reproach, the Congress of the United States, and the several branches thereof, to impair and destroy the regard and respect of all the good people of the United States for the Congress and the legislative power thereof, which all officers of the government ought inviolably to preserve and maintain, and to excite the odium and resentment of all good people of the United States against Congress and the laws by it duly and constitutionally enacted; and in pursuance of his said design and intent, openly and publicly and before divers assemblages of citizens of the United States, convened in divers parts thereof, to meet and receive said Andrew Johnson as the Chief Magistrate of the United States, did, on the eighteenth day of August, in the year of our Lord one thousand eight hundred and sixty-six, and on divers other days and times, as well before as afterwards, make and declare, with a loud voice, certain intemperate, inflammatory and scandalous harangues, and therein utter loud threats and bitter menaces, as well against Congress as the laws of the United States duly enacted thereby, amid the cries, jeers and laughter of the multitudes then assembled in hearing....

For an important treatment of this, see Jeffrey Tulis's The Rhetorical Presidency, coming out in November in a new edition.