Valmiki Ramayana Yuddha Kanda Sarga 9 Shloka 8

तात: father, यः one who takes, अर्थः I ask, त्रिभिः of the three (Sama, Dana and Bheda), उपायैरपि: means also, प्राप्तम् attained, नशक्यते: not possible, तस्य: his, विक्रमकालान् heroic deed, युक्तान् diligently, मनीषिणः intelligent, आहुः yes.

"Dear father, intelligent people say that an act which cannot be accomplished by the three means (Sama Conciliation, Dana Gift, Bheda Sowing dissension), should only be accomplished diligently by one's heroic deed. Therefore, we should think of war only after the above three means are employed."