An interesting piece of show history, which was presumably planned for development in the currently-in-limbo "Caprica" series is the First Cylon War. This took place between 40 and 50 years before the current series. The Cylons were in robotic form, and as a cute touch, looked like the Cylons from the original 1978 series.

Here are hints that have leaked out:

• The Cylons were created by a corporation owned by the Graystone Family.
• Joseph Adama, father of William, was a civil rights lawyer and opponent of the Graystones.
• The original script for Caprica had a strong slavery focus. This suggests both that they were not going to shirk from the concept of the Cylons as slaves, and possibly that it was the slavery that Joseph Adama fought.
• William Adama as about 11 years old during these political battles.
• Tigh, a member of the Final Five, fought in this war, but for the colonial side.
• The colonies were not united before the war. Their Articles of Colonization were signed at around the time of the war. It is suggested the Cylon threat united otherwise more insular colonies.
• Caprica seems to have been the most advanced colony. It developed the Cylons, and was the seat of the new Colonial government.
• The cylons fought did not have humanoid bodies. They were not known to download upon destruction.
• Events took place which, an interview suggests, imply the Cylons had a reason to come back 40 years later and commit their genocide attempt. We presume there were atrocities committed towards the Cylons.
• From the use of the term "toaster" it is clear that the concept of the Cylons as "mere" machines, beneath human contempt, continued to the present day.
• At the end of the war the Cylons fled into space. An armistice station was created but never visited by the Cylons. They kept careful watch on the boarder.
• In their explorations of space after the war, the Cylons found and explored Kobol.
• It is suggested Cylons were primarily made for military and hard labour roles. It is not clear what their military purpose was -- this suggests the Colonies themselves had frequent military conflicts.
• If this is true, it is not suprising there should be resentment against Caprica, if that colony created the threat that both brought ruin on the colonies, and brought them together. The choice of Caprica as the seat of government must have been a politically difficult one.
• There was an anti-computer backlash after the war, slowing development of cybernetic systems, but it didn't stop newer battlestars from having them.

Some speculation:

• The Final Five, who predate the new generation of Cylons made by the Graystones, must have had some role in all of this. Did they try to interfere to stop the slavery? Did they assist in the construction of the Cylons with a people for whom the technology seems quite advanced?
• What happened to the Graystones? Were they lynched? Where they killed, frankenstyle, by the Cylons?
• If Joseph Adama opposed the Cylon creation, and was so right, was he a hero? Or was he an evil Cylon-lover because he opposed creating them in slavery?