The unit was commanded by Captain George Magruder Patterson who was appointed 2nd Lieutenant in Battery B of the Sumter Battalion 16 April 1862, and Captain on 21 July. His unit at Gettysburg suffered 2 KIAs, 8 wounded with 25 of their horses put out of commission. He continued in command of the battery at Fredericksburg, Chancellorsville, Gettysburg and on at least to Petersburg in late 1864.
The tablet, also called the Patterson's CS Battery Tablet, is southwest of Gettysburg on West Confederate Avenue, on the left side of the road if traveling in a northerly direction, 260 feet southeast before the left turn for Berdan Avenue (which is northwest of this position) and north of Pitzer Woods. 
The monument faces the west, right into the setting sun. Parking can be had at the side of the road at small, intermittently placed cutouts. Please do not park on the grass, park on the side of the road. I cannot emphasize that enough! You will be ticketed. I visited this monument on Saturday, March 10, 2012 at 3:01 PM, just before the clocks were set ahead for the Spring. I was at a 584 foot ASL elevation.
These monuments were first built in 1900 and concluded in 1906 according to the NRHP nomination form. Some sites have the monuments being erected in 1912 or 1911; the NRHP also has this specific one at 1910. It is amazing with all the work and effort exerted to make the Gettysburg National Military Park a reality, no one took the time to keep accurate records and correct installation dates. 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.
Draw the Sword, with descriptive help from the NPS site, offers the following description: Cast iron tablet, 3’8? x 3’4?, with raised inscription painted in a contrasting color and mounted on fluted cast iron post. All 4’4? H. Tablets casts by Calvin Gilbert. The inscription on the 3.8' x 3.4' tablet narrates the events associated with Battery during the Battle.
Army of Northern Virginia
Hill's Corps Anderson's Division
Lane's Battalion Patterson's Battery
Two Napoleons, Four 12 pounder Howitzers
July 2 Was detached from the Battalion in the morning together with the Howitzer of Ross's Battery and ordered into position here. In the afternoon opened fire upon the Union positions north of Peach Orchard and when the infantry advanced at 6 p.m. moved forward with it beyond the Emmitsburg road and was engaged there until dark.
July 3 Occupied a position near here in reserve and did not take part in the active operations of the day.
July 4 Withdrew about sunset and began the march to Hagerstown.
Losses Killed 2, wounded 5, missing 2.
Ammunition expended 170 rounds.
Horses killed or disabled 7.
There are scores of similar monuments for the various Confederate States & Union units which fought at Gettysburg. Four designs represent brigade, division, corps and army headquarters, and each has elements which identify it as Union or Confederate. Many of the tablets were created by Albert Russell & Sons Co. of Newburyport, Massachusetts and are made of granite, bronze and concrete or like this one, cast iron. All of these tablets were designed by architect E.B. Cope. He designed pretty much every tablet for both the Union and Confederate armies, each one distinct, with several different varieties. The monuments 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 set 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
Information about these specific types of monuments:
CONFEDERATE BATTERY AND BRIGADE TABLETS (ADVANCED POSITION)
These tablets are 3’8" x 3’4" in dimensions, with carefully prepared inscriptions cast in raised letters painted in white (contrasting the black background) describing the part taken in the battle by each brigade, their position and stating its numbers and losses so far as practicable to obtain. 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. The advance position markers were cast by Calvin Gilbert. SOURCE & SOURCE
The Patterson’s Georgia - CS Battery 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 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 MN588-B.
From the Nomination Form:
Civil War Tablet that marks position of Patterson's CS Battery on July 2-4, 1863. Narrates events associate w/ Battery during Battle.
Short Physical Description:
MN & 2 Cannons. Cast iron tablet, 3'8" x 3'4", with raised inscription painted in a contrasting color and mounted on fluted cast iron post. All 4'4" H. Cannons on N/S side of tablet.
Long Physical Description:
Located on E side of West Confederate Ave, nearly opposite Berdan Avenue. All cannons have been removed from this site, only cannon pads remain.
My Sources
1.
NRHP Nomination Form
2.
Stone Sentinels
3.
Virtual Gettysburg
4.
Draw the Sword
5.
Historical Marker Database
6.
Antietam on the Web