A late autumn/winter subterranean survey at Fort McNair has literally unearthed new findings, while answering but posing new questions regarding past historical structures and events that once occurred on the installation peninsula in southwest Washington, D.C.
The report entitled, “Phase I Archaeological and Geophysical Survey of the District of Columbia Penitentiary and Washington Arsenal Sites at Fort McNair,” was prepared for Joint Base Myer-Henderson Hall’s Directorate of Environmental Management by URS of Herndon, Va. An objective of the search was to conduct field work providing additional exploration of the burial sites of those found guilty of conspiracy in the assassination of President Abraham Lincoln, the gallows site, the U.S. penitentiary and the Washington arsenal location, which were once located on what is now Fort McNair.
According to the DEM and URS, the report findings were mixed during the total field work which ran from November 2011 through February 2012.
“One of the objectives of the archaeology investigation was to obtain physical evidence to support interpretation of the Lincoln assassination conspirator trial room [in Bldg. 20], which has just been reconstructed. The lack of findings relating to the penitentiary is disappointing,” JBM-HH architectural historian Kristie Lalire said. “However, the original penitentiary wall was located during the investigation and that element, along with overlay maps produced by URS in the archaeology report, will assist in locating markers for the gallows and adjacent graves, complementing the trial room re-creation. And of note, is the archaeology report, which will become a very valuable reference resource. Finally, a surprising outcome of the investigation was the findings at the Washington Arsenal site, which are rich and varied, providing an incentive for additional research on the 19th century installation.”
During the geophysical scan of the arsenal site, a new, unknown anomaly was discovered at the Washington Arsenal/Southeast War College and the parade ground sites and additional investigation was recommended.
“While I was not surprised to find some of the building foundations from the Washington Arsenal, I did not expect so much of the foundation elements or the historic ground surface to still be intact and preserved underneath the parade ground,” said URS archeologist Scott Seibel who considers the arsenal finds the most exciting revelations of the mission. “The confluence of the historic research, geophysical survey, and archaeological investigations produced great results in this area. Additionally, we encountered a dense layer of gravel and cobbles of a likely historic origin but unknown purpose to the south of the War College initially identified during the geophysical survey. It is proof that archaeological investigations almost always produce some level of new mystery.”
Like the adjacent penitentiary site, the temporary gravesites of the Lincoln conspirators —Mary Surratt, Lewis Powell, David Herold, and George Atzerodt — who were hung in July 1865, have “seen a significant amount of disturbance over the past few decades,” according to Seibel.
“The results of the geophysical investigation did reveal the former location of the southeastern perimeter wall of the penitentiary, but did not reveal any evidence of grave shafts that were located adjacent to this wall,” he said. “While it is likely that remains of the temporary graves may no longer exist, it would take mechanical excavation to strip off the upper soil layers to reveal the 1865 ground surface and determine if the grave shafts still remain or have been destroyed.”
In the report summary, URS noted that any remains of the penitentiary’s main cell block have been “completely destroyed as a result of the construction and demolition of the large traffic circle that once was located in the area.”
According to Seibel, the aforementioned traffic circle was demolished in the late 1800s and the early 1900s.
Along with uncovering five prehistoric and 299 historic artifacts, the investigation also revealed major demolition debris pits of brick, slag, kitchen and window glass, coal and slate fragments. The prehistoric findings were small “lithic debitage” or shavings from the sharpening or resharpening of a stone projectile point. A lead artillery shell fuse cap that may date to the Civil War era was also unearthed during the Fort McNair dig.