不斩来使 / Envoy Killing Taboo
Envoy killing taboo / 不斩来使 is the diplomatic norm 《资治通鉴·周纪》53丨秦惠王用张仪换地皮 uses to explain why killing 张仪 could help 秦国 even if 楚国 satisfied 楚怀王’s desire for revenge. The host says states at war generally did not kill envoys, so Zhang Yi’s death in Chu would supply Qin with a stronger claim to punish Chu.
The norm matters because Zhang Yi is both the hated deceiver from the earlier Shangyu promise trap and a Qin envoy in the later exchange. Chu’s private revenge impulse therefore runs into public diplomatic cost.
The concept is useful for reading why Qin Huiwen Wang’s calculation can be two-sided. If Zhang Yi survives and is used, Qin may gain 黔中; if Zhang Yi is killed, Qin gains a war pretext. The norm turns a personal death into interstate legitimacy.
Key Claims
- A hostile court may want revenge against an envoy, but killing him changes the diplomatic and military justification available to the sending state.
- Diplomatic norms can protect individual messengers while also being exploited as pretexts by stronger states.
- The norm makes Zhang Yi’s risk legible as both personal danger and Qin strategic leverage.