The translator goes on to explain that the Big One is blind in its right eye. Theoretically, it would be possible to approach it from its right side. You suggest this to the guards, and they agree that it would be a good strategy, except that the Big One knows we would try this and so always has lots of lizards around to guard its right side.
There are enough crisscrossing tunnels that it might be possible to catch it off guard, if you knew which tunnel it was traveling by. Unfortunately, there are too many possible paths and too few men to station to them all in hopes of getting lucky.
The Princess has moved on to speak to the guards. The translator informs you that you are stationed near this particular gate to fight. He will stay with you, but the Princess will move to higher ground to get a better vantage point and direct the fighting.