The enemy really has no strategy behind their madness. They will keep sending lines of men to try and kill you and most likely they will sucede. To enjoy this game to the fullest you have to defend your base, I found this more of like a tower defense game truthfully. Build pillboxs, watchtowers, tanks, howitzers, bombers, fighters, and they cant take your base. Unfortunatley enough for me they used morters to soften down my defenses, effectivley killing me, it was a smart thing that the AI did, and I had no way to counter attack them.
It is a decent game, if you can get it for around 5 dollars, get it. Its well worth it, especially since its a ww1 game.