Matthew Henry Commentary Deuteronomy 21:10-14

"When thou goest forth to battle against thine enemies, and Jehovah thy God delivereth them into thy hands, and thou carriest them away captive, and seest among the captives a beautiful woman, and thou hast a desire unto her, and wouldest take her to thee to wife; then thou shalt bring her home to thy house; and she shall shave her head, and pare her nails; and she shall put the raiment of her captivity from off her, and shall remain in thy house, and bewail her father and her mother a full month: and after that thou shalt go in unto her, and be her husband, and she shall be thy wife. And it shall be, if thou have no delight in her, then thou shalt let her go whither she will; but thou shalt not sell her at all for money, thou shalt not deal with her as a slave, because thou hast humbled her." — Deuteronomy 21:10-14 (ASV)

By this law, a soldier was allowed to marry his captive if he wished. This might take place on some occasions; but the law does not show any approval of it. It also suggests how binding the laws of justice and honor are in marriage, which is a sacred engagement.