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 its morale and create a counter-ambush opportunity instead of producing easy collapse.

Current Synthesis

Hanji 1023 frames the concept 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 then prevents the rule from becoming simplistic. The first pursuit fails because Cao Cao personally commands the rear guard; the second pursuit succeeds because Cao Cao has moved faster with light cavalry and left a weaker rear guard under other generals.

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, and timing, not only on whether the enemy appears to be retreating.
• 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.

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.

Counterevidence & Qualifications

This is currently a one-source concept. The Sunzi maxim is not a universal ban on pursuit: the same episode says Zhang Xiu’s second pursuit succeeds once Cao Cao is no longer personally holding the rear and the remaining guard is weaker. The concept should therefore be used as a condition test, not as a rule that retreating armies should never be attacked.

What Changed

• Created the concept from Hanji 1023’s Anzhong pursuit sequence and Jia Xu’s two-stage advice.

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.
• 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.