Inauguration of Andrew Johnson
The inauguration of Andrew Johnson as the 17th president of the United States was held on April 15, 1865, on the third floor of Kirkwood House in Washington, D.C., following the assassination of President Abraham Lincoln. The inauguration marked the commencement of Andrew Johnson's only term (a partial term of ) as president. Chief Justice Salmon P. Chase administered the presidential oath of office. This was the third non-scheduled, extraordinary inauguration to take place. News reports had it that the oath was administered at 11 a.m. that day. After the ceremony, President Johnson gave an impromptu inaugural address, which began with him begging the cabinet to remain with him and then attacking the Confederate States of America with such venom, that one witness remarked "It would have been better had he been struck dumb." As President Lincoln lay dying, Vice President Johnson visited the room where he lay. When Mrs. Lincoln saw him, she reportedly screamed and demanded he be removed, so he went back to his room at Kirkwood House. According to newspaper reports, Johnson had gotten severely inebriated, and when aides to the now-dead Lincoln came to fetch the new president they were unable to wake him for several minutes. When he was finally awake, the accounts read, "he had puffy eyes and his hair was caked with mud from the street," and that a barber and doctor were summoned to clean him up for the 10 a.m. ceremony, which most accounts agree went smoothly. However, there are other accounts, believed more reliable by some, that refute this claim. List of witnesses 
 
Most of what is known about the swearing-in of Johnson comes from one wire report: "Andrew Johnson was sworn into office as President of the United States by Chief Justice Chase to-day at eleven o'clock." The ceremony was witnessed by members of the cabinet and "a few Congressmen." Attorney General James Speed (1812–1887)
 Treasury Secretary Hugh McCulloch (1808–1895)
 Postmaster Montgomery Blair (1813–1883)
 Blair's father Francis Blair Sr. of Maryland (1791–1876)
 U.S. Senator Solomon Foot of Vermont (1802–1866)
 U.S. Senator Alexander Ramsey of Minnesota (1815–1903)
 U.S. Senator Richard Yates of Illinois (1815–1873)
 U.S. Senator William M. Stewart of Nevada (1827–1909)
 John P. Hale of New Hampshire (1806–1873)
 U.S. Representative John F. Farnsworth of Illinois  (1820–1897)
Ramsey, Stewart, and Yates were members of the United States Senate at the time of Andrew Johnson's 1868 impeachment; all three voted to convict. According to James G. Blaine, the swearing of the oath was attended by "all the members of the Cabinet except" Secretary of State Seward (who had been gravely wounded by the conspirators against Lincoln's government), meaning that Gideon Welles, John Palmer Usher, and William Dennison Jr. would also have been present. McCulloch, who served as Treasury Secretary for the remainder of Johnson's term and who has been called "the only real defender of Johnson," described the ceremony in his 1888 memoir:

Ad hoc inaugural address
Per the New York Times, Johnson's first statement, which served as an inaugural address under the circumstances, was as follows:

According to James G. Blaine, this statement was poorly received. In his memoirs published in the 1880s, Blaine wrote, "The effect produced upon the public by this speech, which might be regarded as an Inaugural address, was not happy. Besides its evasive character respecting public policies which every observing man noted with apprehension, an unpleasant impression was created by its evasive character respecting Mr. Lincoln. The entire absence of eulogy of the slain President was remarked...While he found no time to praise one whose praise was on every tongue, he made ample reference to himself and his own past history. Though speaking not more than five minutes, it was noticed that I and my and me were mentioned at least a score of times." See also
 Presidency of Andrew Johnson
 Reconstruction era

References

United States presidential inaugurations
1865 in American politics
Inauguration
Inauguration of Andrew Johnson
1865 in Washington, D.C.
April 1865 events