Answer:
   
   There are really two questions here:
   
   Question 1: Does Halacha Permit Jews to Own Slaves?
   
   First, note that "Slavery" in the Torah generally refers to temporary
   indentured servitude to one's creditor. Such slavery was permitted
   under Jewish law. However, the treatment of Jews towards their slaves
   was much more humane than that of the surrounding culture, for a key
   element of Judaism is to remember that Jews were once slaves in Egypt
   (in fact, this is the central theme of the holiday of Pesach).
   
   In Judaism, the slave was protected. Exodus 21:2-11 defines the rights
   of the servant. Quoting from the Hertz Penatateuch and Haftorahs:
   
     Slavery, as permitted by the Torah was quite different from Greek
     and Roman Slavery, or even the cruel system in some modern
     countries down to our own times. In Hebrew law, the slave was not a
     thing, but a human being; he was not the chattel of a master who
     had unlimited power over him. In the Hebrew language, there is only
     one word for slave and servant. Brutal treatment of any slave,
     whether Hebrew or heathen, secures his immediate liberty.
     
   Jewish law required that a slave could go free in the seventh year of
   service (Exodus 21:2), although his family would not be freed;
   although if he came into servitude with a wife, that wife would also
   be freed. The slave could, however, indicate that they perferred
   bondage to freedom. Every fiftieth year (the "Jubilee"), the slaves
   with their families would be emancipated, and property (except house
   property in a walled city) would revert to its original owner. (Lev
   XXV:8-55).
   
   In Judaism, there is also the concept of an "Eved Canani", a
   non-Jewish slave, who is the property of a Jew, as is discussed in
   Vayikrah 25:46. This concept of slavery is nothing like slavery that
   occurred in America to the Negroes. The slaves were not kidnapped, but
   rather were purchased from themselves; i.e., they were offered a sum
   of money, or guaranteed shelter and food, in exchange for becoming
   slaves. The obligation to treat your slave humanely applies to both
   Jewish and non-Jewish slave, as does the obligation to make sure they
   have all necessary comforts, even at the expense of their master's own
   comfort (e.g., if there are not enough pillows for all, the master
   must provide his slaves with pillows before himself).
   
   Slavery is clearly discussed in the Torah, especially in reference to
   Canaan, who was cursed by his grandfather Noach to be destined to be
   the slaves to the rest of mankind, as stated and repeated a number of
   times in Beraishis 9:25-27.
   
   Is slavery moral? We live in a society where same sex marriages,
   partial-birth abortions, and mercy killings are considered moral by
   many--and perhaps even the majority--of our society. Additionally, it
   is considered "sport" to watch two men get together in a ring, and
   attempt to injure each other, and we roar in approval when one has
   managed to draw blood from the other and knock him unconscious. We
   must realize that what we consider moral or immoral is the sum total
   of the society in which we live. In Judaism, we've been blessed with
   the Torah, which tells us very clearly what is moral and immoral, and
   directs us to elevate ourselves above our society and accept the
   Torah's definition of morality. When the Torah says that theft is
   forbidden, this is not because society has determined that theft is
   forbidden, but because G-d is telling us so. Hence, it is forbidden to
   steal even in situations that society would not necessarily consider
   it theft, such as pirating software from large corporations.
   Additionally, when the Torah tells us that there is a Mitzvah to
   eradicate Amalek (evil) from the face of the earth (Shemos 17:14-16,
   and Devarim 25:17-19), as difficult as it is for us to swallow this,
   we must realize that this is the moral thing to do. This means, that
   when a Jewish doctor was summoned to save little Adolf Shicklegruber's
   life when he was an infant (later known as Adolf Hitler), rather than
   save his life, he should have smothered him to death (assuming that he
   knew that he is from Amalek). Of course, everyone there would have
   been horrified--but can you imagine how much less the world would have
   suffered had he realized that there is a divine code of morality that
   is higher than his own understanding and society's definition of what
   is moral and immoral! Similarly, when we find the concept of slavery
   in the Torah, while we certainly may and should question and try to
   understand, it must be with the realization that our Torah is actually
   the only code of morals that we have that we can be certain is correct
   (based on our beliefs), and we must accept the Torah whether it fits
   into our own preconception of what is moral and what is not.
   
   Question 2: Did Jews own Slaves?
   
   It is true that some Jews in the Southern U.S. before the Civil War
   did own slaves (alas), and there were intense antebellum debates on
   the subject; for example, Rabbi Morris Raphall of Congregation B'nai
   Jeshurun in New York, preached a sermon in 1861 defending slavery,
   while David Einhorn of Baltimore, a committed abolitionist, was forced
   to flee town. Additionally, recent research [FABER, ELI : Jews,
   Slaves, and the Slave Trade: Setting the Record Straight. ; New York
   University Press, (1998)].suggests that Jews in the Caribbean held
   slaves in numbers approximately similar to non-Jews of equivalent
   socio-economic strata. However, Jewish Law prohibts treating a slave
   like chattel and abusing him or her.
   
   A good site with information on Jewish participation in the Civil War
   is [5]http://www.jewish-history.com/civilwar.htm