The 4th Maine Infantry served as a member of Ward’s Brigade in Birney’s Division of the Third Corps, Army of the Potomac, a Fighting 300 Regiment. The 4th Maine Volunteer Infantry Regiment was assembled in Rockland, Maine on By May 20, 1861 with Colonel Hiram G. Berry as its commanding officer. The regiment was mustered out of service July 19, 1864, with the expiration of their term. The veteran volunteers and recruits were transferred to 19th Maine Infantry. Of the 1440 men that served in the regiment during the war 170 men were killed in action or died of wounds received in battle. An additional 443 were wounded, 137 men perished of disease, and 40 men expired in Confederate prisons. At Gettysburg, the fourth infantry was commanded by Colonel Elijah Walker (1818-1905). Walker was a lumber merchant in Rockland. He was wounded at Gettysburg on July 2 and again at the Wilderness. Capt. Edwin Libby (1832-1864) took command after he was injured, who was killed at Wilderness. Under Walker's command, the fourth Maine infantry brought 332 men to Gettysburg and among them, 11 were killed, 59 were wounded and 74 went missing.
The 4th Maine Position Monument is located on the right or east side of 
Hancock Avenue (RD310) if traveling north along the road at an area called The Angle. The monument is directly across the road from the High Water Mark of the Rebellion Monument (MN230) and the Copse of Trees. The 1st New York Independent Battery Monument (MN231-B) is also right across the road, southwest of this position and the 106th Pennsylvania Infantry Monument (MN229-C) is also across the road, northwest of this position. On this side of the road and across the road, there are about 1080 feet of green fields with a line of monumentation spread across it representing the line of union regiments who defended Cemetery Ridge at The Angle against Longstreet's assault also referred to as Pickett's Charge on July 3, 1863, the final day of the Great Battle. 
Parking is plentiful and is available road-side at intermittently enlarged shoulder cut-outs, usually marked with white striping. Be sure to keep vehicles off the grass or you will be ticketed by park police. I visited this monument on Tuesday, August 7, 2012 at approximately 5:06 P.M. I was at an elevation of 594 feet, ASL. I used a Canon PowerShot 14.1 Megapixel, SX210 IS digital camera for the photos.
Often, state regiment monuments are also accompanied by secondary monument which designate positions maintained from July 1-3, 1863 as well as flank monuments to delineate the ends of troop lines. The primary 4th Maine Infantry Monument (MN126-C) located at Devils Den (the regiments location on July 2) has two flanking markers, and this position marker. I was surprised to learn this position marker given its size, age and location does not have an individual listing on the NRHP. The position monument shows the regiment's location supporting the Union defensive line during Pickett's Charge. The primary monument, flank markers and this third day position monument were all dedicated on October 3, 1889 by the State of Maine. The marker are composed of granite. The red granite diamond symbol of the Third Corps appears on the side of the monument. The top section of the marker also forms a diamond, the symbol of Third Corps. The monument is about 4 feet high on a roughly hewn base, larger then the monument, about a foot high. The front is narrow and the sides are wide, like looking at the front of a house with a roof coming down on either side. Additional details from the nomination form concerning the position stone may be found below in red. There are inscriptions on the right and left sides which read:
(Right):July 3 in support here
Captain Edwin Libby
In Command
(Left):July 2 engaged at Devils Den
Colonel Elijah Walker
in command wounded
The 4th Maine Infantry Monument & position monument are contributing features 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 and secondary markers and monuments are collectively identified as structures number MN126-C.
From the Nomination Form:
Marks position held by 4th Maine Infantry during p.m. of July 2, 1863. 1 of 15 mns in Park to Maine commands at Gettysburg. Located near present entrance to Devil's Den. Position marker marks location of regiment on July 3, 1863 - Located on Hancock Ave.
Short Physical Description:
Mn, 2 flank markers & 1 position marker. Mn set on boulder. 5-sided double base, each side 6'w, 2'4" high. Granite shaft, 5-sided each side 2'9"w, Overall 12' high. Inscription on all sides. Flank markers, slant faced, 1'6"x1'x2'.
Long Physical Description:
N/A
My Sources
1.
NRHP Nomination Form
2.
SIRIS
3.
Stone Sentinels
4.
Virtual Gettysburg
5.
Draw the Sword
6.
Historical Marker Database
7.
Wikipedia
8.
Find a Grave