Factual error: At the start of the war, it says Fort Sumter 1861. However, on the battlefield we see the US flag with 35 stars. In April 1861, there were only 33 states.
Factual error: After the Fort Sumter battle, Mary Todd sees the newspaper on Lincoln's desk which states "20,000 soldiers dead", and what appears to be an April 1861 date (which makes sense since that's when the Battle of Fort Sumter took place.) However, there were zero causalities at that battle. And the first major battle, First Battle of Bull Run in late 1861, didn't even see 1,000 causalities.
Factual error: After Lincoln is president, there is a scene of an official reading a document outside the White House. From the angle at the man's feet pointed up, the modern electrical lights in the ceiling are visible.
Factual error: When Abraham and Speed are hiding in the belltower, Speed bumps into the bell's pulley and it tolls loudly. The nudge wasn't hard enough for the bell's clapper (pendulum) to hit the side of the bell.
Answer: Adam wanted to turn the whole nation into vampires. And as head vampire, he would be the leader. Part of the plot line was vampires feed on slaves, so Adam wanted to keep slavery legal. During the course of the Civil War, Adam conspired with Jefferson Davis to send vampires to the front line to help with the war for the South, in return for claims to the North for his clan (although he would probably turn on the South afterwards).
Bishop73