In The Gettysburg Address, Lincoln uses the word "dedicated" twice within the first two sentences. He starts off his speech with
Fourscore 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.
In this passage, Lincoln is referring to the nation as being dedicated to equal rights for all men. In other words, the American citizens are the ones who should be dedicated to the fight for equal rights. Additionally, the government was founded on this concept, so it can also be interpreted that the government is who Lincoln is referencing with the word dedicated.
Although Lincoln was invited to speak to dedicate land for the National Cemetery, his speech became much more than that. The Battle of Gettysburg was the bloodiest battle of the Civil War, so Lincoln used his persuasive speech to inspire the soldiers to keep fighting. He reminded them that if they gave up, those who lost their lives at Gettysburg would have died in vain. Lincoln's message in The Gettysburg Address is to continue fighting for those rights to determine if the government that was created by our forefathers in 1776 can continue surviving.