He took a tone that was quite lyrical and expressed the need to end the war.
In his gettysburg address Lincoln started to redefine the Civil War as a struggle for human equality not only to save the Union. He extolled the memory of those who died during the Gettysburg battle.
In his second inauguration adress the defeat of the South was very close and he tried to appease his audience by advocating a fair treatment of the South.
One reason is that it shows that it is a part of the rhyme scheme and the other reason is that it highlights the significance of light. Hope this helps!
