'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."

It was 150 years ago Tuesday, in the midst of the Civil War, when President Abraham Lincoln delivered the oration that became known as the Gettysburg Address. The battle at Gettysburg had taken place months earlier in July, but it wasn't until October that the reburial of Union soldiers was begun. Eventually, more than 3,500 men would be interred there.

Lincoln was invited to speak at the dedication of the Soldiers' National Cemetery on Nov. 19, but he almost didn't make it to the ceremony. The day before and the day of the event, Lincoln complained of illness. He made it through the speech but was later diagnosed with a mild case of what may have been smallpox. In addition, Lincoln's son Tad fell ill around the same time. It was a serious matter, as the Lincolns had already lost two sons to childhood illness. However, Lincoln felt the ceremony was too important to miss. Upon his arrival in Gettysburg, he learned his son was recuperating.

In the Gettysburg Address, Lincoln urged listeners to remember the men who had fought and died in the conflict, and rededicated a nation to its ideals of self-government and individual freedom.

The Historical Society of Pennsylvania will commemorate the anniversary of the address with a display of Civil War documents. The free display opens Tuesday and continues through Dec. 31.