In which country was there a civil war between 1861 and 1865, which was lost by the Confederate forces?

Answer 1

It was American Civil War

Among the 34 states in January 1861, seven Southern slave states individually declared their secession from the United States and formed the Confederate States of America.
When Confederate forces entered the state in September 1861, neutrality ended and the state reaffirmed its Union status, while trying to maintain slavery.