According to the sacred Shari’ah of Islam, it is haram (unlawful) to consummate marriage with married women. However, women who are taken captives by Muslim warriors are an exception and marriage with them is permissible under certain circumstances.

God, the Exalted, has permitted marriage contract with a female captive after one assures she is not pregnant from her first husband provided that the captive and her husband should be in two different places. If the woman and her husband are taken captives along with each other, she will not be halal for anyone other than her husband. This order is not applicable to the battles fought between two nations even though one of them might be the oppressor and transgressor.

The reason and philosophy behind Islam permitting marriage with female captives can be explained as follows: While the capture of women as prisoners is an unfortunate and bitter outcome of battles between warring nations, it is also a reality that is common to both the past and the present. Undeniably, the women that were captured and taken captive in wars were a part of the enemy’s army, and to release them would only assist the enemy in recuperating their lost numbers and strengthening their army. As a result, it would be completely illogical to release these captives unconditionally. In addition, keeping them in custody was also not a proper solution.

A feasible solution would be to employ these captives in positions of work such as mines, agricultural fields, etc., but this would mean denying them the fulfillment of their sexual drives which could give rise to very undesirable complications, moral and ethical degradation of the women. If these prisoners have their emotional and physical needs met within reasonable limits, these adverse effects can be avoided.  Furthermore, if a big number of people are excluded from the society, the consequences would be graver because it would give rise to an impure generation in the society, a generation that will end up taking a position against moral and ideological values. In other words, they would represent the enemy’s thought and ideology and if this stance is not adopted, then there would come into being a population which is practically incompatible with the moral values of the society. Therefore, Islam officially recognized the permissibility of conjugal relations with them under specific circumstances. Such relations are thus considered within the realms of Islamic Shari’ah and intended to improve the social well-being of the parties concerned and society at large.

For further information vide: answer 1076 (site: 2541).