While many of us studied, or even memorized the speech as school children, I think some important context from the address is not commonly transmitted in 5th grade history classes.
I refer to the fact that a series of distinguished speakers were invited to the event for the purpose of addressing a crowd that could sense the end of the war. Each did their best to infuse the ceremony with importance which, for most, meant that they spoke for a very long time. They searched for the words and conjured the metaphors that they felt would best resonate with the historical significance of the day.
As the President, known for powerful oratory, and delivering the final words of the day, Lincoln took the podium facing enormous expectations from the crowd. They settled in, ready to have their emotions stirred during a long, hot soak in the tub of verbal eloquence.
Rather, he dismissed the ceremony as more or less meaningless compared to the honor already bestowed on the grounds at Gettysburg by the brave soldiers who had died there. He spoke for about 2 minutes and then took his seat. The crowd was stunned.
I find this context fascinating. If you are also intrigued, here is a great summary of background information that went into his development of the Gettysburg message.
Also, if you re-read the address (below), it is easy to see why the other speakers went home, shaking their heads, and muttering "Why didn't I say that?"
Lincoln's Address at Gettysburg
November 19, 1863
Four score and seven years ago our fathers brought forth on this continent a new nation, conceived in liberty, and dedicated to the proposition that all men are created equal.
Now we are engaged in a great civil war, testing whether that nation, or any nation so conceived and so dedicated, can long endure. We are met on a great battlefield of that war. We have come to dedicate a portion of that field, as a final resting place for those who here gave their lives that this nation might live. It is altogether fitting and proper that we should do this.
But, in a larger sense, we can not dedicate, we can not consecrate, we can not hallow this ground. The brave men, living and dead, who struggled here, have consecrated it, far above our poor power to add or detract. The world will little note, nor long remember what we say here, but it can never forget what they did here.
It is for us the living, rather, to be dedicated here to the unfinished work which they who fought here have thus far so nobly advanced. It is rather for us to be here dedicated to the great task remaining before us—that from these honored dead we take increased devotion to that cause for which they gave the last full measure of devotion—that we here highly resolve that these dead shall not have died in vain—that this nation, under God, shall have a new birth of freedom—and that government of the people, by the people, for the people, shall not perish from the earth.