Effective Strategy

I think the most effective strategy in Sunzi's Art of War is "The army survives by treachery." When the army appeared to be incompetent when it is competent,appeared to be inprepared to fight when it is prepared, appeared to be retreating when it is advancing,appeared to be advancing when it is retreating,the other army would relax their vigilance and then get a failure.In my oppinion,treachery shows the wisdom and is the most effective strategy which helps the army win the war.