In this scenario, you have to defeat enemy's in some order. I'm not telling. You will get the right way as the game progress. British is your main enemy. So don't go there unless you have a massive number of units.If you feel slow, decrease the settings.
v2 Update : Cleared some bugs. And some more action added. Take a quick look at the first screen just after loaded, to get some idea about , in what order you should approach each territory.