January 10, 1861 Florida delegates approved secession of the state from the Union.

March 11, 1862, St. Augustine's city council surrendered the city to Union forces. September of that year, the Preliminary Emancipation Proclamation was read giving freedom to the enslaved in St. Augustine.

On January 1, 1863, Lincoln's official Emancipation Proclamation is read to the public in St. Augustine.

Congress passed the 13th Amendment, abolished slavery and involuntary servitude, on January 31, 1865, was ratified on December 6, 1865 and proclaimed on December 18. 

Ratified on February 3, 1870, as the third and last of the Reconstruction Amendments, the Fifteenth Amendment prohibits the federal government and each state from denying a citizen the right to vote based on that citizen's "race, color, or previous condition of servitude."

Introduction information from:

St. Augustine's Written History
Wikipedia Article - 13th Amendment
Wikipedia Article - 15th Amendment