Final answer:
Abraham Lincoln understood the purpose of the war in 1865, which was to reunite the nation and end slavery.
Step-by-step explanation:
In 1865, Abraham Lincoln understood the purpose of the war was to reunite the nation and end slavery. His view on the purpose of the war had changed since the Gettysburg Address in 1863, where he emphasized the importance of preserving the Union. However, by 1865, Lincoln recognized that the war had become a moral struggle against slavery and he believed that freeing the southern slaves would bring a speedy end to the war.