《周书·列传·卷二十》
当时在战场上交战，未能施行服丧的制度，要替父母服齐斩丧的，都穿黑色丧服参加战事。
于时疆埸交兵，未申丧纪，服齐斩者，并墨缞从事。
When fighting on the battlefield, if unable to mourn according to the prescribed mourning period, those who were to wear black mourning clothes to mourn their parents would join the battle in black mourning clothes.
<s>[INST] Take each pair of old and new sentences and unite them into a single translation that captures the core meaning: Archaic: 于时疆埸交兵，未申丧纪，服齐斩者，并墨缞从事。 Updated: 当时在战场上交战，未能施行服丧的制度，要替父母服齐斩丧的，都穿黑色丧服参加战事。 [/INST] When fighting on the battlefield, if unable to mourn according to the prescribed mourning period, those who were to wear black mourning clothes to mourn their parents would join the battle in black mourning clothes.</s>
Take each pair of old and new sentences and unite them into a single translation that captures the core meaning: Archaic: 于时疆埸交兵，未申丧纪，服齐斩者，并墨缞从事。 Updated: 当时在战场上交战，未能施行服丧的制度，要替父母服齐斩丧的，都穿黑色丧服参加战事。
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When fighting on the battlefield, if unable to mourn according to the prescribed mourning period, those who were to wear black mourning clothes to mourn their parents would join the battle in black mourning clothes.
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