The correct answer is the Battle of Antietam. 
The Battle of Antietam was the bloodiest battle in the Civil War. Roughly 22,000 were killed. However, this battle gave the Union a victory in terms of strategic location. This "victory" gave Lincoln the confidence to issue the Emancipation Proclamation. The Emancipation Proclamation stated that slaves "in all rebellious states" (meaning the Confederacy). This did not sit well with the Confederates and practically all the states ignored it since they considered themselves part of another country anyways. 
        
                    
             
        
        
        
  Nixon and Wallace took advantage of the rising discontent among the conservatives and positioned themselves as defenders of property rights. The increasing level of violent protests had served to aggravate equal feelings against the civil right movements especially among conservative supporters.
        
             
        
        
        
A reason why the Civil War lasted four years is that the Union had to fully conquer the South.
 
        
             
        
        
        
The answer is (b.) the first gulf war
The first gulf war is between the coalition forces led by the US against Iraq. It is also know as Persian gulf war, Kuwait war, first Iraq war, or Iraq war. It started on August 2, 1990 and ended on February 28, 1991. While the six-day war is the conflict between Israel and Egypt in 1967 and Yom Kippur War in 1973.