What is "milk al-yamin" (right-hand possession)? Is marriage a condition to acquire milk al-yamin, and how can it be acquired and terminated?

If Muslims overpower warring disbelievers, the fate of the men is determined by the Imam's discretion, based on what serves the best interest, choosing between execution, ransom, pardon, or enslavement. As for women, they become concubines (malak yamin), and male children become slaves, divided among the mujahideen. The reason for enslavement is disbelief and fighting against Allah and His Messenger. The Imam may grant pardon or ransom for the sake of benefit. Islam has limited the source of slavery to prisoners of war. Islam has honored enslaved women by making them the sole property of their owner, prohibiting anyone else from cohabiting with them. It also granted them the right to gain freedom through mukataba (a contract of manumission) and encouraged their emancipation. It is not a condition for a mujahid to be married to acquire a concubine (malak yamin), and the owner may sell the female slave or the male slave. A man is not permitted to have sexual intercourse with a female slave except after one menstrual cycle for the purpose of ensuring she is not pregnant, or until she gives birth if she is pregnant. This is based on the Prophet's (peace be upon him) saying: "It is not lawful for a man who believes in Allah and the Last Day to irrigate the crop of another."