Who was pres. lincoln talking to at the beginning of the movie? what did they recite?

At the begging of the movie Lincoln was talking to the soldiers. That wouldn’t be anything special in itself but what makes this unique is that he was talking to both the African-American and the Caucasian soldiers. What was recited was one of the best-known and one the most important speeches in the American history, the Gettysburg Address which was given by Lincoln.