A map of every recorded battle based on Wikipedia

I like it! I spent an enjoyable 10 minutes clicking around and checking out what battles took place at various places I have lived in the US and Europe. Is there any way of adding country/US State boundaries for the more geographically-challenged among us? I can usually find my way around using the coastline and following rivers, but I get lost in the middle of large continents occasionally.

Is the increased density in Western Europe caused by unintended bias on Wikipedia (more likely to be documented) or that those places were more war hungry?