Answer :
The "great task" in this passage is the preservation of the Union.
President Lincoln gave this speech after the events of the Civil War between the South and the North. He tried to say that it was their duty to mend the Union and to honor all those people who died during the war, protecting the Union.
President Lincoln gave this speech after the events of the Civil War between the South and the North. He tried to say that it was their duty to mend the Union and to honor all those people who died during the war, protecting the Union.