To what extent did Lincoln’s "Gettysburg Address" speech reflect the changing nature of American society?

President Abraham Lincoln’s speech, delivered at the dedication of the cemetery for the fallen Union troops at Gettysburg, Pennsylvania is important both for the events it commemorated and for the sentiments he expressed. Because the United States was divided into two countries at that time, any understanding of “American society” in the early 1860s must take into account the deep schism in the ways that Union and Confederate people regarded themselves as American.
The battle at Gettysburg, which lasted from July 1–3, 1863, came to be regarded as one of several turning points in the war. General Lee had decided to march his troops north into Union territory, from Virginia through Maryland (a Union state) and into Pennsylvania. It was not only the largest battle fought to date, involving some 85,000 men, but also the bloodiest, resulting in 50,000 casualties. Had Lee’s army succeeded, the Southern forces would have been well positioned to surround and possibly capture Washington, D.C. They were roundly defeated, however, and the surviving troops had to retreat back into Virginia. Lee’s forces never again invaded the North, which meant that the rest of the war was fought in Confederate territory, with the South in a defensive position.
By the time Lincoln gave his speech, four months had passed since the battle, so its impact was acknowledged. The war had been going on for two and a half years, and the heavy burden was felt on both sides. Lincoln wrote and spoke only 272 words, and he emphasized both unity and continuity. Rather than bring up the Northern victory, he referred to the principles upon which the United States had been founded. He stressed that the soldiers had died for the whole country so that “the Nation might live.” He concluded with the simple but effective repetition of “the people” to remind everyone that the nation and the government meant them. In this regard, he reflected the values of the Union, as it was dedicated to making the country whole again, but not of the Confederacy, which was equally dedicated to having two countries where before there had been just one.