• Type: IX-inch Dahlgren Smoothbore shell gun, Serial No. 277
• Year of Manufacture: 1859
• Tube Composition: Cast Iron
• Bore Diameter: 9 inches
• Standard Powder Charge: 13 lbs.
• Projectiles: 90 lb. Shells, 150 lb. Solid Shot
• Tube Length: 131 inches (undamaged)
• Tube Weight: 9164 lbs. (undamaged)
• Range (at 15°): up to 3,450 yards (1.96 miles)
• Invented By: John A. Dahlgren USN
• Casting Foundry: Tredegar Foundry
• Current Disposition: Fredericksburg Area Museum, VA
• Coordinates: 38.3033, -77.460417
• Special Notes: Although this gun is displayed as the "Merrimac Gun", it may be better referred to as the "CSS Virginia Gun"

On March 8, 1862, the CSS Virginia, formerly named USS Merrimac, encountered and defeated the Union ships, USS Cumberland and USS Congress, near Newport News, VA.

This gun was one of the six Dahlgren guns mounted on the CSS Virginia. It was apparently the forward-most port (left) broadside gun (gun #2, Midshipman Marmaduke, under the command of Lt. Hunter Davidson). As the Virginia approached the USS Cumberland to ram her, the Cumberland gunners inflicted the only serious damage ever done to the Virginia. At the same instant as it fired, this gun was hit by a shot from the Cumberland. One man was killed and several wounded, including Midshipman Henry H. Marmaduke. Despite the obvious damage to this gun, they continued to use it but it kept setting fire to the two feet of wood on the inboard side of the iron shield. One other gun was also damged during this engagement.

On the next day, the CSS Virginia engaged in battle with the USS Monitor. This was the famous confrontation between the first two ironclad ships. The outcome was called a draw, but it changed naval warfare.

Rear Admiral John A. Dahlgren developed these bottle-shaped guns. They were considered some of the safest ever made and had a range of 4500 yards.

After the war, this gun was displayed by the Washington Navy Yard. From 1960, it was exhibited at the Dahlgren Naval Base as a reminder of its namesake. Today, it resides on the grounds of the Fredericksburg Area Museum in the historic Fredericksburg district.