The 2nd United States Infantry served as a member of Burbank’s Brigade in Ayres’ Division of the Fifth Corps, Army of the Potomac. The unit was commanded by Major Arthur T. Lee (1814-1879), a native of Northumberland, Pennsylvania. Lee was a career soldier. During the Civil War, he was wounded here at Gettysburg on July 2. Capt. At that time, Samuel T. McKee (1841-1864) took command of this unit from Lee. McKee was a native of Birmingham, Pennsylvania. He was wounded almost 10 months prior to Gettysburg at Sharpsburg, Maryland otherwise known as the Battle of Antietam. McKee was killed by guerrillas April 11, 1864. The infantry unit has 237 men engaged at Gettysburg and suffered 6 casualties with 55 wounded and 6 men who went missing.
The 2nd U.S. Infantry - US Regulars Tablet can be found off of Ayres Avenue on the right or southwest side of the road if traveling in an easterly direction on Ayres. The tablet faces the road in a northeastern direction. There are several other of these Regular United States Infantry tablets. This wooded area is called Rose Woods. The Wheatfield would be just to the rear, having left it 225 feet to the west. Parking is available at small, cutout shoulders along the road, some wide, some narrow. This area is tricky however as it marks the beginning of a wide, semi-circular of a turn which begins a few feet ahead. There is a small to on the other side of the curve to park safely and there is a small trail to bring visitors back to this monument. I parked there and picked up several ticks walking through the wood to reach this monument. The apex of the turn is particularly noteworthy as it offers a memorable view of Little Round Top which is .34 miles away to the southeast. Be sure to stay off the grass or you will be ticketed by park police. I visited this monument on Thursday, July 5, 2012 at 1:34 P.M. I was at an elevation of 547 feet, ASL. I used a Canon PowerShot 14.1 Megapixel, SX210 IS digital camera for the photos.
The monument 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: One of 45 monuments erected to units of the United States regular army on the battlefield. A red polished Jonesboro granite monolith that is set upon a concrete foundation with a descriptive 3’6'x3’7' bronze tablet with the coat of arms of the United States in bronze. The inscription on this tablet reads:
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Army of the Potomac
Fifth Corps
Second Division Second Brigade
Second U.S. Infantry
Six Companies
Major Arthur T. Lee and Captain Samuel A. McKee
commanding
July 2 Arrived in the morning and took position with the Brigade at the right of the Twelfth Corps. Skirmished with the Confederates. Later moved to the left. At 5 p.m. formed line with left on north slope of Little Round Top and the right of Brigade line extending into some woods. Advanced across Plum Run and to the crest of the rocky wooded hill in front near the Wheatfield and facing left occupied the stone wall on the edge of the woods. The Confederates having opened fire on the right flank and advanced through the Wheatfield in the rear the Brigade was withdrawn under a heavy Infantry fire on both flanks and from the rear and of shot and shell from the Batteries and formed in line on right of Little Round Top.
July 3 Remained in same position.
Casualties. Killed 1 officer and 5 men. Wounded 4 officers and 51 men. Missing 6 men.
There are hundreds of non-sculpted monumentation for the various Confederate States & Union units which fought at Gettysburg. There are about 10 different variations of tablets, markers & 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 & regimental monuments for U.S. Regulars & Confederate have their own distinct design (2), bringing the total to 10 designs at the battlefield. The bronze tablets were created by Albert Russell & Sons Co. of Newburyport, Mass. The granite bases which accompany the various tablets were created by the Van Amringe Company from Boston, Mass. The cast iron tablets were manufactured by 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 & Rebel armies, each one distinct, w/ 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 were erected just after the turn of the century during the first & 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 & tablets were erected by the Gettysburg Park Commission (established by the War Dept.). 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 & 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 and can be found HERE. The initial 1893 report up to & including 1921 can be found here. 1922 to 1926 are missing & have yet to be discovered. The years 1927 to 1933 were discovered in 1996 and are also included. To my knowledge this is the most comprehensive list of documents that illustrated the development and formation of the park.
Information about these specific types of monuments:
UNITED STATES REGULARS TABLETS
Forty-two monuments honor units of the regular army to fight at Gettysburg. Other sources have the amount at forty-four tablets while I have personally counted 48 of these monuments. These regiments and batteries were designated as United States Regulars as opposed to the state volunteer forces. These polished granite monuments with bronze plaques affixed to the front were fabricated by the Van Amringe Granite Company, of Boston and authorized in 1907. They were completed in the autumn of 1908. Each consists of Jonesboro granite, 24 by 50 inches and 7 feet high, set upon concrete foundations, and upon each is fastened a descriptive bronze tablet and the coat of arms of the United States. are similar in appearance to and often mistaken for headquarters, since they have the same curved-and-scrolled top on the bronze tablet as corps and army headquarters. The difference is that instead of being square, the stone comes to a peak in the center on the U.S. Regulars monuments, with a brass Great Seal of the United States centered within the peak. SOURCE & SOURCE
The 2nd U.S. Infantry - US Regulars Tablet is a contributing feature to the Gettysburg Nat'l Military Park H.D. which is nationally significant under NR Criteria A, B, C & D. Areas of Significance: Military, Politics/Gov't, Landscape Architecture, Conservation, Archeology-Historic. Period of Significance: 1863-1938. The monument is designated as structure no. MN645.
From the Nomination Form:
1 of 44 US Regulars Tablets in Park. Locates positions occupied by Regular 2nd Infantry during Battle of Gettysburg, July 2, 1863. Located W side of Ayres Ave.
Short Physical Description:
Red granite monolith w/rough-hewn sides & back, 4'2"x2', 7' high. Gable top. Polished face w/bronze inscription tablet, 3'6"x3'7" and bronze seal w/ US Coat of Arms, 1' in diameter, on face above tablet.
Long Physical Description:
N/A
My Sources
1. NRHP Nomination Form
2. Stone Sentinels
3. Virtual Gettysburg
4. Draw the Sword
5. Historical Marker Database