I've actually mastered memorizing the Gettysburg address in 7th grade and now I'm going to 8th grade and the tone that Abraham Lincoln used as he read his speech was a calm but serious tone. In his speech(mid half of his speech) he said " we are met on a great battlefield of that war. " and "we have come to dedicate a portion of that field as a final resting place for those who here gave their lives that, that nation might live" you notice that his tone in those two main parts are calm and serious. This also applies to the rest of the speech. Lincoln's speech is one of the greatest speech of all times because his speech was a message to the soldier's both from the Union and Confederates side who fought in Gettysburg. I hope this message answers your question.
