It is permissible to have intercourse with a female captive after it is established that she is not pregnant, and if she has a husband, then her marriage is annulled when she is captured

Abu Sa'id al-Khudri (Allah her pleased with him) reported that at the Battle of Hanain Messenger of Allah ﷺ sent an army to Autas and encountered the enemy and fought with them. Having overcome them and taken them captives, the Companions of Allah's Messenger (may peace te upon him) seemed to refrain from having intercourse with captive women because of their husbands being polytheists. Then Allah, Most High, sent down regarding that:" And women already married, except those whom your right hands possess (iv. 24)" (i. e. they were lawful for them when their 'Idda period came to an end).

حَدَّثَنَا عُبَيْدُ اللَّهِ بْنُ عُمَرَ بْنِ مَيْسَرَةَ الْقَوَارِيرِيُّ، حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، حَدَّثَنَا سَعِيدُ، بْنُ أَبِي عَرُوبَةَ عَنْ قَتَادَةَ، عَنْ صَالِحٍ أَبِي الْخَلِيلِ، عَنْ أَبِي عَلْقَمَةَ الْهَاشِمِيِّ، عَنْ أَبِي سَعِيدٍ، الْخُدْرِيِّ أَنَّ رَسُولَ اللَّهِ ﷺ يَوْمَ حُنَيْنٍ بَعَثَ جَيْشًا إِلَى أَوْطَاسٍ فَلَقُوا عَدُوًّا فَقَاتَلُوهُمْ فَظَهَرُوا عَلَيْهِمْ وَأَصَابُوا لَهُمْ سَبَايَا فَكَأَنَّ نَاسًا مِنْ أَصْحَابِ رَسُولِ اللَّهِ ﷺ تَحَرَّجُوا مِنْ غِشْيَانِهِنَّ مِنْ أَجْلِ أَزْوَاجِهِنَّ مِنَ الْمُشْرِكِينَ فَأَنْزَلَ اللَّهُ عَزَّ وَجَلَّ فِي ذَلِكَ { وَالْمُحْصَنَاتُ مِنَ النِّسَاءِ إِلاَّ مَا مَلَكَتْ أَيْمَانُكُمْ} أَىْ فَهُنَّ لَكُمْ حَلاَلٌ إِذَا انْقَضَتْ عِدَّتُهُنَّ .

Abu Sa'id al-Khudri (Allah be pleased with him) reported that Allah's Apostle ﷺ sent a small army. The rest of the hadith is the same except this that he said: Except what your right hands possessout of them are lawful for you;
and he did not mention" when their 'idda period comes to an end". This hadith has been reported on the authority of AbuSa'id (al-Khudri) (Allah be pleased with him) through another chain of transmitters and the words are: They took captives (women) on the day of Autas who had their husbands. They were afraid (to have sexual intercourse with them) when this verse was revealed:" And women already married except those whom you right hands posses" (iv. 24)

وَحَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، وَمُحَمَّدُ بْنُ الْمُثَنَّى، وَابْنُ، بَشَّارٍ قَالُوا حَدَّثَنَا عَبْدُ، الأَعْلَى عَنْ سَعِيدٍ، عَنْ قَتَادَةَ، عَنْ أَبِي الْخَلِيلِ، أَنَّ أَبَا عَلْقَمَةَ الْهَاشِمِيَّ، حَدَّثَ أَنَّ أَبَا سَعِيدٍ الْخُدْرِيَّ حَدَّثَهُمْ أَنَّ نَبِيَّ اللَّهِ ﷺ بَعَثَ يَوْمَ حُنَيْنٍ سَرِيَّةً . بِمَعْنَى حَدِيثِ يَزِيدَ بْنِ زُرَيْعٍ غَيْرَ أَنَّهُ قَالَ إِلاَّ مَا مَلَكَتْ أَيْمَانُكُمْ مِنْهُنَّ فَحَلاَلٌ لَكُمْ وَلَمْ يَذْكُرْ إِذَا انْقَضَتْ عِدَّتُهُنَّ .