This is simply an invasion map simulating the movie Zulu. Invasions of spearmen grow progressively larger until a maxmimum of 600 spearmen attack in the 12th invasion. I completed this on Hard difficulty level, but it may not be as difficult as is sorta fun. If you make it to the last invasion, you probably will have it wrapped up. One word of warning... keep at least one or two woodcutter posts inside your outpost. If you run out of wood, you're dead.
You could make many woodcutters post at the beginning to make sure to have plenty of wood, but then, there are no more trees... So you have to balance between getting wood and letting the trees expand... I never used the flammable pitch but it can be helpfull to some. Apothecary is just here for decoration and don't need to be used. I played this map in hard, which I recommend, and enjoy to play it again, from time to time... A nice map.