Ancient thoughts on waging war are perhaps still relevant today. The ideal situation envisaged by Sunzi in The Art of War is to overcome the enemy without a fight through diplomatic and other means to frustrate the enemy’s plans, isolate and demoralized the enemy to break his will.
The ancients had always exhorted that arms should only be used as a last resort. Just because a state has great military power, it should not bully a weaker state. To the ancients, benevolence and righteousness are requisite in waging a war otherwise there can be no complete victory. But leaders today tend to think differently. What Sunzi wrote more than 2,500 years ago could be relevant to waging modern wars of today:
“By Tao, I mean that which causes the people to be in harmony with their leaders, so that they will accompany them in life and unto death without fear of mortal peril. (Harmony arising from the leaders’ benevolence and righteousness – Chang Yu) (In happiness at overcoming difficulties, people forget the danger of death – Book of Changes)
By command I mean the general’s qualities of wisdom, sincerity, humanity, courage, and strictness.” (Chapter I Estimates) [Also refer to the second line of Hexagram 7 Shi / The Army]
“Victory is the main object in war. If this is long delayed, weapons are blunted and morale depressed. When the army engages in protracted campaigns the resources of the state will not suffice. Thus, while we have heard of blundering swiftness in war, we have not seen a clever operation that was prolonged. There has never been a protracted war from which a country has benefited.”
Thus those unable to understand the dangers inherent in employing troops are equally unable to understand the advantageous ways of doing so. Those adept in waging war do not require a second levy of conscripts or more than one provisioning. They carry their equipment from the homeland; they rely for provisions on the enemy. Thus the army is plentifully provided with food.
Treat the captives well, and care for them. This is called ‘winning a battle and becoming stronger’.
Hence what is essential in war is victory, not prolonged operations. And therefore the general who understands war is the Minister of the people’s fate and arbiter of the nation’s destiny.”
(Chapter II, Waging War [Sun Tzu, The Art of War translated by Samuel B Griffith])
Winning a war without winning the hearts of your own people and that of the conquered people cannot be considered a complete victory. Resentment and resistance will arise especially from unrighteous wars. Think Afghanistan in the 1980s and Iraq recently.