Returning Army Interdiction Risk / 归师勿遏式追击风险

Definition

Returning Army Interdiction Risk / 归师勿遏式追击风险 is the risk that blocking or pursuing a force trying to return home, rescue its rear, or escape a route crisis can harden morale and create counter-attack danger unless the command situation shows that resolve is missing.

Current Synthesis

Hanji 1023 frames the danger side through Cao Cao’s Anzhong withdrawal and Jia Xu’s two pursuit judgments. Zhang Xiu and Liu Biao try to exploit Cao Cao’s retreat by blocking dangerous terrain, but the pressure gives Cao Cao a death-ground opportunity: he opens a narrow path at night, signals escape, draws the allied force into pursuit, and strikes from front and rear. Jia Xu’s advice prevents the rule from becoming simplistic. The first pursuit fails because Cao Cao personally commands the rear guard; the second pursuit succeeds because Cao has moved faster with light cavalry and left a weaker rear guard under other generals.

Hanji 1063 adds the inverse test at Ye. Cao-side generals fear that Yuan Shang’s rescue force is a returning army and should not be blocked, but Cao Cao asks what Yuan Shang’s route reveals. A main-road approach would suggest a willingness to stake everything on saving Ye; the western-mountain route suggests a preserved exit. Yuan Shang’s later surrender request, night flight, and loss of supplies confirm that the maxim is a diagnostic problem, not an automatic ban on attack.

Key Claims

• A retreating or returning army can become more dangerous when its route, rear security, and survival objective all point in the same direction.
• Blocking a return path can convert an enemy’s logistical problem into forced resolve rather than automatic collapse.
• Pursuit judgment depends on commander location, rear-guard quality, terrain, timing, and whether the enemy’s conduct shows resolve or a fallback path.
• Conditions can reverse after first contact: a failed pursuit may be followed by a successful one if the main commander leaves and the rear guard changes.
• False escape can make the blocking side abandon advantageous terrain and enter a prepared ambush.
• A rescue army can be attacked when its route choice reveals caution, exit preservation, or weak death-fight commitment.

Evidence

• Returning-army pressure: Hanji 1023 uses the Sunzi phrase “归师勿遏” to interpret why stopping Cao Cao’s withdrawal can make his force harder, not easier, to defeat.
• Death-ground conversion: Hanji 1023 reports Cao Cao’s own explanation that Zhang Xiu and Liu Biao created the pressure point he needed for victory at Anzhong.
• Commander-location test: Hanji 1023 has Jia Xu explain the first failed pursuit through Cao Cao’s personal rear-guard command and the second successful pursuit through Cao Cao’s later light-cavalry departure.
• False-escape lure: Hanji 1023 records Cao Cao’s night path and feigned escape drawing the full Zhang-Liu force into ambush.
• Route-choice test: Hanji 1063 says Cao Cao distinguishes between Yuan Shang coming by the main road, which would call for avoidance, and coming by the western mountain route, which makes attack appropriate.
• Resolve confirmation: Hanji 1063 has Yuan Shang take the western route, request surrender before encirclement is complete, flee at night, and lose supplies and command objects.

Counterevidence & Qualifications

The Sunzi maxim is not a universal ban on pursuit or interdiction. Hanji 1023 says Zhang Xiu’s second pursuit succeeds once Cao Cao is no longer personally holding the rear and the remaining guard is weaker. Hanji 1063 says Yuan Shang’s rescue force can be attacked because his route and later conduct do not show true no-retreat resolve. The concept should therefore be used as a condition test, not as a slogan that retreating or returning armies are always untouchable.

What Changed

• Added Hanji 1063’s Ye relief-force test, where Cao Cao uses Yuan Shang’s route choice to decide whether “归师勿遏” applies.
• Reframed the concept from a pursuit warning into a broader diagnostic rule about resolve, fallback paths, and commander conduct.

Related Concepts

• 死地战术前提 - overlapping morale-pressure concept for when no-retreat conditions create usable resolve.
• 诱敌离位 - false escape can pull blockers or pursuers out of safe terrain.
• 战场信息控制 - pursuit and escape signals work by shaping what the enemy thinks is happening.
• 战利品实证瓦解士气 - downstream Ye tactic after Yuan Shang’s weak relief commitment is exposed.
• 行势情战略评估 - broader framework for judging action by conduct, situation, and human commitments.
• 《孙子兵法》 - textual frame for returning-army and death-ground reasoning.