According to article il of the constitution, one of the president's duties is to
serve as commander in chief.
create laws and interpret them
set up and manage the courts.
serve in the house and senate.

Serve as commander in chief

Explanation:

Hope this helps, if wrong comment

abraham lincoln  (february 12, 1809  – april 15, 1865) was an american statesman, politician, and lawyer who served as the 16th  president of the united states  from 1861 until  his assassination  in april 1865. lincoln led the nation through the  american civil war, its bloodiest war and its greatest moral, constitutional, and political crisis.[2][3]  he preserved the  union,  abolished slavery, strengthened the  federal government, and modernized  the u.s. economy.

when he becomes king