The 27th Connecticut Infantry served as a member of Brooke’s Brigade in Caldwell’s Division of the Second Corps, Army of the Potomac. In its nine months of service, the 27th fought in the three largest campaigns in the eastern theatre of the war. The 27th Connecticut embarked on their last campaign of their nine-month service which culminated with the campaign and Battle of Gettysburg, on July 1, 2 and 3, 1863. Here, in the late afternoon of July 2, the 27th entered the battle with a total of 3 companies only 160 men out of the original 829 who had joined just nine months earlier. They occupied the portion of the union line known as "The Wheatfield," where the regiment successfully held back the rebels. On July 18, 1863, what remained of the 27th was released from the Army of the Potomac and sent back to New Haven to be discharged. In its nine months of service, the Regiment lost 533 men who were killed, wounded, captured, and died of disease out of 829 enrolle
The regiment was commanded by Lieutenant Colonel Henry C. Merwin (1839-1863), who was killed here on the second day of the battle. Merwin was a businessman from New Haven before the war. Merwin led 160 men into battle at Gettysburg. Lt. Colonel Merwin led the 27th Connecticut Infantry Regiment through Fredericksburg and Chancellorsville. He was mortally wounded during the charge across the Wheatfield on July 2 and Major James H. Coburn took command of the regiment. His last words were, "My poor regiment is suffering fearfully." The 27th Connecticut lost 10 killed, 23 wounded and 4 missing at Gettysburg out of 75 men - a casualty rate of almost 50%. Most of the regiment had been captured at Chancellorsville in May, and it mustered only two companies at the Battle of Gettysburg.
The 
monument to Lieutenant Colonel Henry Merwin is south of Gettysburg along Wheatfield Road on the north edge of the Wheatfield. The monument was erected in 1880 at the location in the Wheatfield where Lieutenant Colonel Merwin was mortally wounded. In 1885 the regimental monument was placed at that location by the regimental association and Merwin's memorial was relocated to nearby Wheatfield Road, with this additional inscription at the bottom of the monument added:
In Memory of
Lt. Col.
Henry C. Merwin
27th C.V.
who fell mortally
wounded where
the monument of his
regiment now stands.
The are two monuments dedicated to this regiment as well as two minor ones as well. The primary monument, also called the 27th Connecticut Infantry Monument, is located near Ayers Avenue in the Wheatfield. That monument marks the location where Lieutenant Colonel Merwin was mortally wounded on July 2nd, and was dedicated by the 27th Connecticut Regimental Association on October 22, 1885. Much smaller markers also show where the regiment's Lieutenant Colonel Merwin and Captain Jed Chapman fell, and the advanced position of the regiment.
The 27th Connecticut Infantry Monument is located on the right or east side of Detrobriand Rd when traveling north, pushed back a bit in the woods. I believe this area is called Rose Woods. This road is a crazy unorganized loop which originates and ends at Sickles Road. This sculpture is almost directly across from the midpoint of the entrance and exit (or vice versa) of this road along Sickles Road. 
Parking is available along the side of the road at intermittently enlarged shoulders. Take care to park in the white lines or on asphalt widened shoulders and not park on anything remotely green looking as Park Police will happily ticket you. I visited this site on Monday, July 1, 2013 on the 150th anniversary of the Battle of Gettysburg after 5 PM, EDT & @ an altitude of 542 feet, ASL. As always, I used my trusty and oft abused Canon PowerShot 14.1 Megapixel, SX210 IS digital camera for the photos.
The Draw the Sword site helped out by the NPS narrative and the SIRIS site (and me) offers the following description: Rectangular, granite, sarcophagus monument about 6 feet high with a peaked cap stands on a rough-hewn base. Relief elements include the State of Connecticut coat of arms, and crossed muskets and sabers on both sides. The State of Connecticut appropriated $1,000 for the work which was dedicated by the State of Connecticut on April 17, 1889.
There are conflicting reports as to when the 27th Connecticut Infantry Monument was dedicated by the State of Connecticut. The NPS is writes the 1889 as the installation date. SIRIS writes the sculpture was installed between 1886 and 1893 and dedicated on October 22, 1889. Stone Sentinels reports it was dedicated by the State of Connecticut on April 17, 1889. believes it was placed and dedicated on October 27, 1889 as does the HMDB site which lists the year as '89 but gives no month and date. I just don't know. What I so know is the entire thing is of granite and overall the monument is 4 feet 10 inches x 7 feet 5 inches². Naturally, I was unable to recover any information on the artisans employed to create the monument. There are inscriptions on the front and back which reads:
(Front):27th Conn. Vol's.
4th Brigade.
1st Division.
2nd Corps.
Advanced position
of this regiment
in the
Brigade charge
July 2nd 1863.
(Back):Erected by the Commonwealth of Connecticut
As a Memorial to the Valor of Her Loyal Sons
The 27th Connecticut Infantry Monument is a contributing feature to the Gettysburg National Military Park Historic District which is nationally significant under NR Criteria A, B, C & D. Areas of Significance: Military, Politics/Government, Landscape Architecture, Conservation, Archeology-Historic. Period of Significance: 1863-1938. The original National Register Nomination was approved by the Keeper March 19, 1975. An update to this nomination was approved by the Keeper on January 23, 2004. The monument is identified as structure number MN144.
From the Nomination Form:
Marks advance position of 27th Connecticut Infantry after its charge through the Wheatfield in late afternoon of July 2, 1863. 1 of 8 mns in Park to CT troops at Gettysburg. Located E of Brooke Ave in Rose Woods.
Short Physical Description:
Rough hewn base, 5'11' sq. -Shaft 2'3" sq. w/ hipped & ridge course cap. Raised regimental name & inscription on shaft, relief state seal on W face. Reliefs of muskets & saber on both ends. Polished panels w/ inscription on E face.
Long Physical Description:
N/A
** Please note the NRHP page has listed the wrong picture. There are two monuments for this regiment and it seems it was just too much to get the pictures straight. **
My Sources
1.
NRHP Nomination Form
2.
SIRIS
3.
Stone Sentinels
4.
Virtual Gettysburg
5.
Draw the Sword
6.
Historical Marker Database
7.
Wikipedia