Four monuments honor Connecticut regiments that took part in the Battle of Antietam. A fifth regiment sometimes listed as being present, the 5th Connecticut Infantry, was actually on detached service in Frederick, Maryland as of September 15th.

Monument to the 8th Connecticut Infantry at Antietam 8th Connecticut
Infantry Regiment
 Monument to the 11th Connecticut Infantry at Antietam 11th Connecticut
Infantry Regiment
Monument to the 14th Connecticut Infantry at Antietam 14th Connecticut
Infantry Regiment
 Monument to the 16th Connecticut Infantry at Antietam 16th Connecticut
Infantry Regiment
Over 50,000 men from Connecticut served in the Union Army during the Civil War. They were organized into 30 regiments of infantry, 1 regiment of cavalry, and 2 of heavy artillery, as well as 3 batteries of light artillery.
Seal of the State of Connecticut from the monument to the 11th Connecticut Infantry

Seal of the State of Connecticut from the 11th Connecticut monument