How did Ambedkar say caste is held together by controlling women?
In 1916, as a student in New York, he read a paper arguing that the essence of caste is a single rule: marriage within the group and never outside it. Everything else — the ranking, the pollution rules, the sealed occupations — follows from keeping the bloodline closed. And a bloodline can only be kept closed by controlling one thing above all: the marriages of women. Caste, on his analysis, is maintained on the bodies of women.
He then showed how the cruelest customs of Hindu society are not random cruelty but the machinery this control requires. A closed group produces, by simple arithmetic, a surplus of widows and of unmarried people who threaten to marry out. The customs exist to dispose of that surplus: the burning of the widow removes her, enforced widowhood locks her away from remarriage, and the marriage of a girl to an older man ties her in before she can choose. Each is a device for keeping women inside the caste's control.
The conclusion matters for anyone who thinks the subjection of women and the caste system are separate issues. Ambedkar argued they are one issue seen from two sides: you cannot free women while the caste order stands, because their subjection is what keeps it standing, and you cannot end caste while women remain property to be married strategically. The control of women is not a symptom of the system but its method.