Final answer:
Lincoln was able to win a second term through Union victories, convincing border states to rejoin, and the lack of opposition from Democrats.
Step-by-step explanation:
Lincoln was able to win a second term because the Union army won some huge victories during the Civil War. These victories boosted morale and support for his leadership. Additionally, Lincoln had convinced four border states to rejoin the Union, which increased his support base. Lastly, the Democrats did not nominate a candidate, which reduced the opposition against Lincoln.
Learn more about Lincoln's re-election