This depends on the country. See related questions or re-ask your question specifying the country.
United States: James Buchanan, replaced by Abraham Lincoln on March 4.
James Buchanan was the fifteenth President of the United States, serving from 1857 March 4 to 1861 March 4.
Abraham Lincoln was the sixteenth President of the United States, serving from 1861 March 4 to 1865 April 15 when he was assassinated.
Abraham Lincoln was the president during the civil war.
Abraham Lincoln was the president during the civil war.
Abraham Lihcoln was the president during the US civil war.
Abraham Lincoln was President during the Civil War.
Abraham Lincoln was the president during the Civil War.
No, Abraham Lincoln was the President during the Civil War.
Abraham Lincoln was the first member of the newly-formed Republican party to be elected President. His term of office spanned the civil war almost precisely.
Abraham Lincoln was president during the US Civil War.
There was no president of Southern Sudan during the civil war.
The Confederate President during the Civil War was Jefferson Davis.
Abraham Lincoln (our 16th President) was President during the Civil War
Abraham Lincoln was President during the US Civil War.