you can only successfully assault the aliens with a full army of green giants and the defensive strategy, set their line to the back and let them walk across the field hammering anything near them until they get to the ranged, if its raining reinforcements after all the ranged is dead let them break rank, to defend have full samurais once again set their line to tear into the ranged, if your numbers are low after the ranged is dead use the 60% revival and wipe it up, keep a samurai defense, while having a full unit or two of green giants to attack them slowly