Final answer:
The opening line of the Gettysburg Address connects the present conflict to the nation's founding principles of liberty and equality, underlining the reasons for the Union's struggle in the Civil War.
Step-by-step explanation:
The first sentence of the Gettysburg Address "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" serves the purpose of forging a link with past events and ideals. Abraham Lincoln recollects the founding of the United States and its core values of liberty and equality to emphasize the significance of the sacrifices made during the Civil War. This connection underscores the continuing struggle to uphold these principles, which were the basis for the nation's establishment and are again the cause for which the Union soldiers fought and died during the Civil War at the Battle of Gettysburg.