Spielberg spoke of the interplay between history and memory, and between memory and justice.
"It's the hunger we feel for coherence, it's the hunger we feel for progress for a better world," he said. "I think justice and memory are inseparable."
The crowd, estimated at 9,000, gave him a standing ovation.
Penn State film major Alison Golanoski, 19, from Gettysburg, said afterward that Spielberg's passion for Lincoln came through.
"He was very invested in Lincoln as a person, and his personality," Golanoski said. "I loved all of it."
The 150th year since the battle will be marked in 2013, particularly around the battle's anniversary in early July.
"Lincoln," which stars Daniel Day-Lewis in the title role, concentrates on the period leading up to the president's assassination in 1865.