I.e. you have a single shape representing the coastline of your map, and a single path representing all the borders inside it, can you use that path to divide the map into territories?
Example: http://i.imgur.com/5aGnm2B.png

EDIT: I found an extension to inkscape that does it https://inkscape.org/en/~Moini/%E2%98%85multi-bool-extension-cut-difference-division (use multi-division tool)

Edited 2/8/2017 16:55:12

This is kinda significant as it means that svg files from wikipedia can easily be turned into warlight maps

dont know if this is possible, but if so I'd like to know how. maybe someone in the help forum may help you out.

Does this help?

http://graphicdesign.stackexchange.com/questions/20196/using-the-shape-of-an-object-to-cut-the-object-beneath-it-in-inkscape

^ Thats what you do for cutting a shape into two, it doesn't work for cutting into multiple shapes.

I found a sort of solution, I editted the original message to show it. It's a bit buggy and takes several minutes to compute for large maps but it works at least.