Okay, William. I've got one for you.
http://www.civil-war-journeys.org/spreadsheetofcivilwarbattles.htm
There is a link to an Excel file at the bottom of the webpage. Among other things, it has the name of the battle, the state in which it was fought, the campaign it was a part of, names of Union/Confederate/Indian commanders, Union/Confederate victory, date ranges for each battle, number of casualties, and whether the battlefield has been preserved for visits today. These things could be indicated by Tooltip (for name of battle, campaign, and names of commanders), color code (for year), or symbol other than a disk (Stars and Bars for a Confederate victory and US flag for a Union victory--the bigger the flag, the more casualties inflicted--might have to be logarithmically scaled).
confederateFlag =
Interpreter["Image"][
File[FindFile[
"C:\\Users\\Glen\\Downloads\\Wolfram\\battle-flag-army-of-\
northern-virginia.jpg"]]]
GeoGraphics[{GeoMarker[
Entity["City", {"Richmond", "Virginia", "UnitedStates"}],
confederateFlag]}]
But then, since a flag would be the symbol used in location, trying to color code it wouldn't make sense or look very good. Perhaps the Tooltip could be color coded for the year. As an example,
TooltipStyle -> {Background ->LightRed}
(However, since your Tooltip only shows up when you hover over the location, you'd lose the visual advantage of seeing a lot of information all over the map all at once.) What to do, what to do... Hmmm...
I'd plug it into your code myself for quick results, but the spreadsheet might need a little help first. Battlefields like Gettysburg, Richmond, and Atlanta will resort to their respective cities, but what about Gaines' Mill and Seven Pines? (I happen to know exactly where these latter two places are. Google Maps doesn't know.) Latitude and longitude coordinates might be necessary for viewing locations of battles. As a further example of the need for coordinates, the "Guide" tab in the spreadsheet explains that the Battle of Marietta, GA had four separate engagements at different places during a month-long period.
I'm sure with just a little more research, I can dig up all the coordinates I need. Well, coordinates for close to 400 listed battles might be more than a little research... I thought I'd give you heads up to see what ideas you had. I'll see what I can get to.
--Glen
