Hi! You can use path-behavior, the starting point being the point they come from, end point the enemies/your base. When two going the opposite direction, they collide obviously. When they do, you stop all path-moving on all enemies and your soldiers. The colliding ones do the fight - which means, they are all standing around waiting for your fight algorithm to decide, which one to destroy - till one of the fighters die. As soon, as one dies, you can start path-movement again, till two collide... and so on.
Basically the age of war is a kind of a turret-defence game but with own soldiers. Did you use that template to start with?