This ancient marriage custom has been practiced in many patrilineal societies. If a man died without heirs, his surviving brother was required to marry the widow so as to continue his brother's family through the son that might be born of that marriage. What is the name for this marriage custom?

Levirate Marriage

Explanation:

The word levirate is derived from a Latin word 'levir' which means brother of husband. Levirate marriage has a long history and it could be seen in different traditions across the globe. However, it is mostly found in societies having strict clan structure and where marrying outside a social group or community is forbidden. In the patriarchal system, it is an important institution as it ensured the protection of a widow and her children.