During his campaign for President, General Harrison had been attacked as being too old to serve as President. Indeed, at age 68, Harrison was the oldest person to run for the office of President. These attacks were unsuccessful. The election was about the economy, and the Whigs had promised to fix it. Harrison was, however, sensitive to the charges that he was too old. When his Inauguration Day arrived, he chose to stand out in the cold, without a jacket, and deliver one of the longest inaugural speeches in American history. A few days later Harrison fell ill. It was assumed that he had caught a cold from standing out in the cold rain for so long without a jacket. Sadly, the cold soon turned into pneumonia. Despite the best efforts of the doctors of the time (usually counterproductive), Harrison died with a month. This was the first time that a President died while in office. Many considered this a national tragedy. Charles Finney, the prominent preacher spoke out on the day of National Fasting, claiming that America was paying for its sins. 

Here are several of the sins Finney spoke about:

The outrageous injustice with which this nation has treated the aborigines of this country. The shameless wickedness of this nation, in respect to the manner in which the Indians have been duped in making treaties with them--the shocking and disgraceful manner in which these treaties have been violated by this government, is almost too bad to name. Who can mention or think of these things, without grief and indignation? How these helpless Indians have been trampled down, and in multitudes of ways oppressed and injured, until their cry has come up into the ears of Jehovah!
2. I notice the hypocrisy of this nation, in shedding British blood in defense of principles which, when applied to their own wrongs, they have always denied. As the very basis of the Revolution, they publicly declared, that "ALL MEN were born free and equal, and endowed by their Creator with certain inalienable rights--among which are life, LIBERTY, and the pursuit of happiness." Now, at the very time at which this declaration was made--the very men who made it--and the nation that proclaimed these truths, as an excuse for revolution and war, stood with their unsanctified feet upon the necks of the prostrate slaves! And from that day to this, this nation as such has continued, publicly and practically, when these wrongs were held up to view, to deny the principles upon which the Revolution was based; while, at the same time, she has, in view of the wrongs received from the mother country, strenuously maintained them--thus at the same time both maintaining and denying these great truths--when herself oppressed, maintaining them and fighting in defense of them--when accused of oppression, denying them, and ready to fight in support of the opposite doctrine.

3. I notice the national treatment of the question of the abolition of slavery, as another of those heinous sins for which this nation ought to blush. Is it not astonishing, that in this government the friends of the oppressed are not even allowed to petition? Our government will not so much as suffer itself to be asked to "undo the heavy burdens." "Concerning oppression they speak loftily." And could we this day meet with the public assemblies in the city of Washington, we might perhaps hear the conduct of Abolitionists, in seeking the abolition of slavery, pointed out as one of the great sins of the people, in endeavoring, as they would express it, "to dissolve the Union."

The death of President Harrison made Vice President Tyler the new President. Tyler insisted that he not be referred to as "acting President", but rather as the President.