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feudal lord
「殿」 has other readings with different meanings.
彼は軍の殿を務めることになった。
He was assigned to serve as the rear guard.
殿の部隊は敵の追撃を見事に防いだ。
The rear guard unit prevented the enemy's pursuit.
退却時に殿を守るのは危険な任務だ。
Protecting the rear during retreat is a dangerous task.