Near as I can tell, the above map is a demonstration of Nodegoat, which is a piece of software for visualizing the data stored in a database. In this case, they took all of the battles recorded in Wikipedia and used that as their data. You can read all the gory (database) details here. You can see a full page version of the map here. Via Detroit Steve.
Update September 2016. Replaced embedded map (which quit working) with a dead image. Follow the link to see the interactive version. Notes about using the interactive version:
- The Key in upper right corner tells you in what era a battle took place.
- The control bar at the bottom can be used to restrict the date range.
- Using the mouse I found I could only get within about 50 years of my desired time. You can get a more accurate slice of time, but it takes a couple of steps:
- Enter your desired start and stop dates in the boxes below the bar. The program is finicky about the format. Dates need to be entered with two digits for the day of the month, a dash, two digits for the month, another dash, and four digits for the year.
- Click on the View Selection button. This will popup a dialog box.
- Look on the line with the magnifying glass icon (the 4th line). Just to the right of this search box is another box with the number '25' and a small triangle. Clicking on this box will popup a list of numbers terminated with the word 'All'. Click on 'All'.
- A 'Processing' message will pop up. Wait until it disappears. If the number of battles is low, you may not see the message at all.
- Click on the X at the upper right corner to close the dialog.