According to History.com, the main idea of the Gettysburg Address is that the sacrifices of those who died on the battlefield of Gettysburg were made to preserve the principles of human equality and self-government as set forth in the Declaration of Independence. Lincoln declared that the survival of the Union depended on finishing the work the buried soldiers started and initiating a rebirth of freedom.
In the Battle of Gettysburg, fought from July 1 to July 3, 1863, heavy casualties were incurred on both sides. The Union army lost 23,000 men, and the Confederates lost 28,000 men. In the end, the Confederates were forced to retreat. Many Union soldiers were quickly buried in badly marked graves, but later a national cemetery was created at the site of the battle. At the dedication, President Lincoln was not the main speaker. Edward Everett, a popular orator, first spoke for two hours on the significance of the battle. Afterward, the Gettysburg Address, only 272 words long, took fewer than two minutes to deliver.
The day after the dedication ceremony, both speeches were reprinted in national newspapers. Democratic journalists found Lincoln's remarks unsuitable and inadequate for the occasion, whereas Republicans praised the speech as a masterpiece. According to History.com, it is the most memorized and quoted speech in American history.