This plugin allows administrators to enter a list of historic events. Events that occurred on this day in past years can then be displayed via the included widget and shortcodes.
You can find more detail and download this Plugin from the WordPress Plugin Directory.
Importing Events
The events are stored in the standard posts table so it is possible to use a standard importer to bulk load your events from a CSV file if you want. I recommend using Really Simple CSV Importer to do this. This is the process:-
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Install and activate This Day in History
Install and activate Really Simple CSV Importer.
Go to Tools -> Import -> CSV -> Choose your CSV file -> Click Upload and Import
This CSV file must be in a particular format. Here is an example file you can download.