Today we unpack one of the most practical and hard-headed military principles from The Art of War · Chapter 2: Waging War: “Speed is valued in war; lengthy campaigns are never favored.”
Before talking about tactics and battlefield victories, Sun Tzu first calculated the staggering economic cost of large-scale warfare. He pointed out that dispatching an army of 100,000 fully armed soldiers costs one thousand pieces of gold every single day, covering chariots, armor, grain transportation, military supplies and daily troop expenses.
Based on this harsh economic reality, Sun Tzu drew an irreversible strategic conclusion: Once a war begins, commanders must pursue a swift, decisive victory. Never drag battles into endless wars of attrition.
In war, prolonged fighting dulls weapons and dampens soldiers’ morale. Sieging fortified cities exhausts military strength. Stationing troops abroad for a long time drains national treasury. If troops grow weary, morale fades, strength depletes and national wealth runs out, neighboring rival states will take advantage of this crisis to launch invasions. Even wise top advisors cannot remedy the disastrous consequences.
Therefore, in warfare, we only accept clumsy but rapid victories; we never pursue sophisticated yet prolonged campaigns.
We can fully understand this timeless military wisdom from three different perspectives: battlefield tactics, national logistics, and geopolitical risks.
Tactical Risk – Long Wars Wear Down All Troops
Sun Tzu’s famous lineWe only accept clumsy speed, never clever delay reveals a straightforward battlefield truth: The sole goal of war is victory, not perfect and complicated battle plans.
No matter how elite an army is, prolonged combat will wear down equipment, drain fighting spirit and slash overall combat effectiveness. Sieging heavily defended cities is the deadliest trap of prolonged warfare. Continuous assaults will exhaust soldiers’ strength rapidly and bring no quick breakthrough. An imperfect but fast strike always beats a flawless but delayed battle plan.
Logistics Risk – Long Campaigns Drain National Wealth
Stationing troops abroad long enough will empty the national treasury. This eight-word sentence exposes the hidden economic burden behind every war.
The most convincing historical case is the decades-long wars between Emperor Wu of Han and the northern nomadic Xiongnu tribes. To eliminate border threats, Emperor Wu launched successive large-scale northern expeditions lasting more than 30 years.
Although Han achieved strategic victory and expelled Xiongnu forces, the endless prolonged wars nearly depleted the national finance, exhausted domestic population and ruined agricultural production. In his later years, Emperor Wu issued a public Self-Criticism Edict, admitting his mistake of reckless and prolonged military expansion that brought severe hardship to the whole nation.
Geopolitical Risk – External Enemies Strike When One State Weakens
The deadliest consequence of prolonged warfare is clearly stated by Sun Tzu: All rival vassal states will launch attacks when your nation falls into wartime exhaustion.
Once a country is trapped in a war quagmire, domestic conflicts and financial crises emerge constantly. Meanwhile, hostile neighboring forces will seize the perfect chance to invade. Facing internal turmoil and external aggression at the same time, no brilliant strategist can reverse the doomed situation.
Classic Historical Case: Wu’s invasion of Chu
Ironically, Sun Tzu’s own monarch, King Helü of Wu, became a perfect negative example violating the principle of swift victory.
In 506 BCE, King Helü launched a full-scale invasion against Chu, assisted by top strategists Wu Zixu and Sun Wu. The Wu army achieved a stunning rapid victory, broke through Chu’s defense line and captured Ying, the capital of Chu. The Chu king fled in panic.
Having achieved decisive victory, King Helü became arrogant and greedy for more territorial gains. He refused to withdraw Wu’s main army and stayed stationed in Chu for a very long time. This prolonged overseas deployment triggered a chain of crises exactly as Sun Tzu warned.
While Wu’s elite army was trapped deep inside Chu with no sign of retreat, the State of Yue took the opportunity to launch a surprise attack on Wu’s undefended homeland. Meanwhile, Chu’s remaining troops allied with Qin’s reinforcement army and launched a fierce counterattack against the overstretched Wu frontline army.
Eventually, the Wu army suffered heavy losses and was forced to retreat completely. Even top military geniuses Wu Zixu and Sun Wu could not remedy this passive situation caused by unnecessary prolonged occupation.
Final Strategic Reflection: Knowing Is Easy, Restraint Is Hard
This historical irony deserves deep thinking: Sun Tzu wrote and advocated swift victory against prolonged war, yet his own ruler ignored this golden rule and paid a heavy price.
War is like fire. Uncontrolled prolonged warfare will eventually burn down the initiator himself. For any competition, whether ancient warfare or modern global competition, timing and timely restraint are always as vital as strength and strategy.
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