When you get to the part where there are two bunkers, hold your squad before you reach the field. Then, take one man and move him behind one of the first boulders. Do this to the rest of the squad then move up. Next, throw smoke grenades so they cannot see you. While the smoke is still there, toss bombs into both of the bunkers. More VC soldiers will enter the bunkers; hurry and move up to the right to the next battle.