The task of preserving the Union has not yet been accomplished.
Explanation:
Abraham Lincoln's famous "Gettysburg Address" is a speech given on the occasion of dedication of the Soldiers' National Cemetery at Gettysburg on November 19, 1863. This speech is is also a dedication of this place to the soldiers who had sacrificed their lives for the safety of the nation.
The phrase "unfinished work" in the speech alludes to the unfinished work of preserving the unity of the Union, the safeguarding of it's people's rights. Lincoln included this words to implore to the people to keep on fighting for injustice and for upholding the unity of the nation. He is also indirectly asking the people to continue the work done by these brave lives lost, encouraging them at the same time.
