I have been researching slavery in Islam in hopes of trying to understand it better. I understand it is abolished now but I have a few questions regarding concubinage.
1.Was the female slave master able to force her into a marriage contract without her consent?
2. Could he acquire a married slave and force her to get a divorce?
There are more important and relevant questions pertaining to one’s Iman than questions pertaining to ruling of concubines.
With regards to your questions, it is mentioned in the books of Fiqh that a master can force his slave in marriage if he sees best interests to protect him/her from Zina etc.
A master cannot force her to get divorce from her husband. A slave when marries with permission of his master and he divorces then his divorce is valid as he has the right to give divorce.
وتزويجها جبرا لأن الملك فيها قائم كما في المدبر
وإذا تزوج العبد بإذن مولاه ثم طلق وقع طلاقه لأن ملك النكاح حقه فيكون الإسقاط إليه
ولا يقع طلاق مولاه علي إمرأته أي إمرأة العبد لأنه لا حق له في نكاحه
(اللباب في شرح الكتاب ٤/١٠٠،٣٠٤ ،دارالبشائر)