The Alleghany Artillery served as a member of Latimer's Battalion, Johnson's Division, Ewell's 2nd Corps. Carpenter's Battery was a famed C.S. artillery unit. The unit lost twenty-six percent of the 91 engaged here. 
The battery was commanded at Gettysburg by Captain John C. Carpenter (January 17, 1839 - December 29, 1912). Carpenter was born in 1839 at Covington, Virginia, serving as Captain of the battery after his brother Joseph was wounded, commanding the battery through many engagements, including 15 major battles. He lost an arm in combat at the Battle of Fisher's Hill, but survived the war.
The tablet is located @ the intersection of Benner's Hill Loop & Hanover Road (PA Highway 116), on the right or west side of the road when traveling south on Benner's Hill Loop. The monument is 669 feet south of the intersection. This tablet is the fourth stopor curiosity along the same side of the road. The first stop turning off of Hanover Road is the 
Graham's Rockbridge Artillery Tablet (MN630-A), followed by Brown’s Chesapeake Artillery Tablet (MN620-A), and finally the Benner's Hill Interpretive, all of which lead to this monument. The monument is flanked by two 12-Pounder Confederate Napoleon guns, both manufactured at the Augusta Foundry of Augusta, Georgia. If facing the tablet, to the right is gun no. 8 AF, to the left, gun no. 30 AF. Parking is available all up and down the narrow road. Take care to 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 @ 1:05 PM, EDT. As always, I used my trusty and oft abused Canon PowerShot 14.1 Megapixel, SX210 IS digital camera for the photos.
These cast iron monuments were first built in 1900 and concluded in 1906 according to the NRHP nomination form as well as the on-line Commission Report archives. Some sites have the monuments being erected in 1910 or later. All of this tablet nonsense is very confusing and seemingly disorganized. 1906 seems to be the most reasonable, extremely conservative date so we will go with that. I have found these tablets mentioned as early as 1902 in the yearly Commission reports with regards to the contracts being awarded. From then on, the tablets were completed in bunches each year as the budget dictated. The work was done under the direction of the Gettysburg National Park Commission (established by the United States Department of War), after they took over the administration of the park from the Gettysburg Battlefield Memorial Association (whose funds had expired) on March 3, 1893, and whose stewardship was then transferred to the National Park Service in 1933. SOURCE
These advance position markers were cast by Calvin Gilbert. Gilbert joined the 87th Pennsylvania Volunteers when the "Rebellion" broke out. Since he was musically inclined, he was made a member of the regimental band. In early 1863, he was promoted to the rank of Captain and sent to Washington D.C. for commissary duty. He served in that capacity until the war ended in 1865, and at war’s end earned the brevet rank of Major. 
After returning home to Gettysburg, Major Gilbert moved his family to the town of Chambersburg, where he served as the Superintendent of Schools. He also opened an iron foundry there in 1868. When Calvin learned, nearly 30 years later, in 1894, that the Gettysburg Foundry was available, he purchased it with a business partner & moved his family back to Gettysburg. For the next twenty years, the Calvin Gilbert Foundry created ironworks that are still seen today on many historic forts and national battlefields (this tablet), from upstate N.Y. to Florida to Lookout Mountain. Gilbert lived to be 100 years old and attended the Last Reunion of the Blue & Gray for the 75th anniversary of the Battle of Gettysburg when he was 99. He was a most remarkable man & lived an amazing life.
There is an excellent excerpt in the American Guide Series about Gilbert attending the 75th reunion anniversary.
Look carefully on the reverse side of one of these tablets and his name might be there; I found a tablet or two like this. The inscription on the tablet reads:
Army of Northern Virginia
Ewell's Corps - Johnson's Division
Latimer's Battalion - Carpenter's Battery
The Allegheny Artillery
Two Napoleons and Two 3 inch Rifles
July 2 The Battery took a prominent part in the cannonade against the Union Artillery on East Cemetery Hill and other points which began about 4 p.m. and continued over two hours. Some of the Union guns on the left enfiladed the Battalion and caused the Battery to suffer severely and having exhausted its ammunition it was ordered to withdraw.
July 3 Remained in reserve and not engaged.
July 4 Withdrew from the field with the Battalion.
Losses - Killed 5 - Wounded 24 - Horses Killed 9
There are hundreds of non-sculpted monumentation for the various Confederate States & Union units who fought at Gettysburg. There are about 10 different variations of tablets, markers and monoliths by my reckoning. Six designs represent brigade (2), division (2), corps (2), & army headquarters (2), each different in a subtle way so as to distinguish between armies. Battalion/battery/advance position markers and regimental monuments for United States Regulars & Confederate have their own distinct design (2), bringing the total to ten designs at the battlefield. The bronze tablets (the brigade monuments) were created by Albert Russell & Sons Co. of Newburyport, Massachusetts. The granite bases accompanying the various tablets were created by the Van Amringe Company out of Boston, Mass. The cast iron tablets were of course manufactured by the aforementioned Calvin Gilbert. The 1910 Gettysburg Commission report lists the awarded contracts to these companies (not Gilbert) for the tablets.
All of these tablets were designed by architect Colonel Emmor Bradley Cope (July 23, 1834 - May 28, 1927). He designed pretty much every tablet for both the Union and Confederate armies, each one distinct, with several different varieties. He is buried in Evergreen Cemetery in Gettysburg, as well he should be as this park and most of the things seen here today were designed by him and as such, are his legacy.
These monuments/tablets were erected just after the turn of the century during the first and beginning of the second decade of the 20th century. Each one has since been preserved or restored at least twice since the turn of the 21st century. The plaques and tablets were erected by the Gettysburg Park Commission (established by the War Department). The Gettysburg Park Commission is also referred to as the Gettysburg National Military Park Commission or the Gettysburg National Park Commission, to clear up any confusions, especially my own.
On October 1, 1898, the Gettysburg National Park Commission in a letter to the Secretary of War gave recommendations for continuing the task of organizing and progressing the work of the Gettysburg National Military Park. Every November they wrote their annual report which outlined the work of the GNPC for that year. The following is an excerpt from that report relevant to this waymark. The link at the end of the paragraph will take you to the entire report. The method of marking the positions of troops on this field, as approved by the War Department, is to place the principal tablet or monument of each command at the position occupied by the command in the main line of battle, and to mark the several important positions subsequently reached by each command in the course of the battle by subordinate and ancillary tablets, with appropriate brief inscriptions giving interesting details and occurrences and noting the day and hour as nearly as possible. SOURCE
Most of the Commission reports have been digitized & can be found HERE. The initial 1893 report up to and including 1921 can be found here. 1922 to 1926 are missing and have yet to be discovered. The years 1927 to 1933 were discovered in 1996 & are also included. This is the most comprehensive list of documents that illustrate the development & formation of the park.
Information about these specific types of monuments:
CONFEDERATE BATTERY TABLETS (ADVANCE POSITION MARKERS)
These tablets are 3’8" x 3’4" in dimensions, w/ carefully prepared inscriptions cast in raised letters painted in white (contrasting the black background) describing the part taken in the battle by each artillery battery, their position and stating its numbers and losses so far as practicable to obtain. Most of the CS battery markers state the losses were not reported in detail. The brigade which each battery served under is written first on the tablet, then proceeded by the battery name, usually accompanied by some colorful artillery name. They are mounted on iron pillars or fluted cast iron posts about 3 feet high, grouted in the ground, and the tablets are inclined at a suitable angle so that the inscriptions can easily be read by persons riding or driving on the avenue. Every tablet is 4’4" in height. SOURCE & SOURCE. These tablets usually have accompanying artillery pieces which flank the tablet on either side. There can be as little as one cannon & as many as four. The cannons usually represent the battery & the armaments that specific battery used at Gettysburg. The cannons presumably point in the same direction as they once fired at the enemy in 1863. Sometimes only the cannon pads are present as the guns are periodically removed for service, cleaning, restoration, maintenance, etc.
The Carpenter's Alleghany Artillery Marker 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 N.R. 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 catalogued as contributing structure number MN621-B.
From the Nomination Form:
Marks position of Carpenter's Alleghany CS Battery July 2-4, 1863. Narrates events associated with the Battery during the Battle. Located at Benner's Hill, south side of PA 116.
Short Physical Description:
Tablet w/ 2 cannon. Painted raised inscription tablet, 3'8"x3'. Mounted on a 4'4" high fluted post. Cannon located left & right of tablet. Tablet cast by Calvin Gilbert, founder.
Long Physical Description:
These 100 tablets locate the positions of batteries and brigades not otherwise marked by monumentation. They consist of cast iron tablets with raised inscriptions painted in a contrasting color and are mounted on fluted cast iron posts. These tablets are scattered throughout the avenue system marking military positions. Those tablets designating artillery positions have from one to four mounted cannons flanking them. Designed by E. B. Cope. They are 4.4 feet high and the tablets are 3.8x3.4 feet.
