Green’s Dictionary of Slang

excrement.

1548		A. Barclay Ecloques (Cunningham) n.p.: For sure the lord’s siege and the rural man’s Is of like savour [F&H].
1603		Jonson Sejanus I ii: I do not ask you of their urines, Whose smell’s most violet, or whose siege is best, Or who makes hardest faces on her stool?
1646		Browne Vulgar Errors n.p.: It accompanieth the unconvertible part in the siege [F&H].
c.1698		B.E. Dict. Canting Crew n.p.: Siege [...] used by Physicians to their Patients. How many Sieges have you had? i.e. How many Stools have you had? Upon taking a Purge, &c.