Season of surprises
October is historically filled with surprises for political campaigns and 2016 was no different for Hillary Clinton and Donald Trump.
Politico has a wonderfully exhaustive look at "October surprises" stretching all the way back to 1840. That year, President Martin Van Buren was seeking re-election. Federal prosecutors got word that the opposing Whig Party in New York committed the "most stupendous and atrocious fraud" in the 1838 midterm election by paying Pennsylvanians to travel to New York vote multiple times in the state election.
Ultimately, William Henry Harrison and the Whigs defeated Van Buren and the Democrats by 6 percentage points.
The election also gave the nation the "Tippecanoe and Tyler too" campaign song, which you surely heard about in your high school government class.
The sheet music for which is here from the Library of Congress: