Geophysics of a War of 1812 Fort

Ground-penetrating radar (along with other kinds of remote sensing) is an emerging field for archaeologists, and it's very exciting. It's also kind of complicated! Happily, Peter Quantock, a graduate student at the University of Denver who is completing his Master's Degree in archaeology, is here to explain it all to us.

Geophysics at Fort Hollingsworth
by Peter Quantock

In recent years, geophysical survey has become an increasingly popular archaeological tool in Maryland.  Archaeologists at sites such as Port Tobacco, Nottingham, and Benedict conducted magnetometry and ground-penetrating radar surveys as part of their investigations. In Jim Gibb’s 5 part series about Fort Hollingsworth on this blog, he talked briefly about the geophysical techniques that were used to help locate the fort.

Today, I’m going to give you a little more information on the ground-penetrating radar (GPR) survey conducted at the site through images of the data. GPR is a technique that collects and records information about the subsurface.  It involves the transmission of high frequency radar pulses from a surface antenna into the ground.  This data is converted into vertical profiles and plan view maps to aid in interpretation.

GPR Gear: GSSI SIR-3000 with 400MHz dual antenna and survey wheel used to conduct the survey at Fort Hollingsworth.

In March 2012, with the help of ASM members and other volunteers, I conducted a GPR survey over top of the magnetometer survey I did the year before.  The goal was to find the trench used at Fort Hollingsworth.  And we were successful! Read all about it in the "Finding Fort Hollingsworth" series on this blog.  

To interpret GPR data we first go to the vertical profile, which allows us to look at the depth of features in the ground.  Below is an example of a vertical profile collected at the site.  This profile runs north south within the larger grid.  It looks like a bunch of sharp, squiggly lines, doesn’t it?  

Yes, it does!

What I see is much different…I see depths and distances of features underneath the ground.  The areas where the black and white reflections are stronger in contrast to the area around it (circled in red in the image below) tell me that there is something of interest there.  These are called high amplitude reflections and they indicate buried features.  THIS is what the fill from the trench looks like in a radar profile!  

These vertical profiles are collected along each transect that is surveyed within the grid.  Our grid was 50m x 50m and we had transects at an interval of every .5 meter.  That gives us 100 vertical profiles to interpret.  We can then put all of these profiles together to create a plan view map.  These are called slice maps.  They are “slices” in time, each representing 10ns of depth (or about 10cm in depth).  The slice map below represents the data from about 30-40cm below the surface…right where the trench fill was located! It's not exactly an underground photograph, but the linear shape definitely suggests the outline of the earthwork we identified here.

The GPR survey conducted at Fort Hollingsworth was a success and great fun!  

Dolley Madison Saves History

For archaeologists, the evidence of the past is mostly found below-ground, but there's an awful lot of history in the structures we see everyday and the landscape they occupy. Bringing us today's above-ground history lesson about how Dolley Madison rescued many of the White House's historical treasures from invading British troops is architectural historian Rebecca Crew. She's got the lowdown on the Bank of Maryland and its role in the War of 1812. Read on!

Perhaps one of the most well-known tales from the War of 1812 is the account of Dolley Madison saving the portrait of George Washington before the White House was torched by the British.  This legend has long-established Mrs. Madison as one of the most popular First Ladies, and one of my personal favorites.  To celebrate the bicentennial of this event, which actually occurred on August 24, 1814, I thought I would attempt to determine where George Washington’s portrait was stashed for safe-keeping, and whether the structure might still exist.

I'm not even kidding, there's a comic about this. 

As soon as she heard that British troops were on their way to burn Washington D.C. in general and the White House in particular, Dolley Madison was ready for action. As she once wrote in a letter to her cousin,“I have always been an advocate for fighting when assailed." (editor's note: You guys, do not mess with Dolley Madison).

With the help of her husband’s teenage slave Paul Jennings, the French-born doorman Jean Pierre Sioussat (also known as John Susé or French John), and the White House gardener Mr. Thomas Magraw (or McGraw), Mrs. Madison loaded up a wagon filled with cabinet documents.  She knew Gilbert Stuart’s portrait of Washington, one of the four Landsdowne portraits, would be too appealing a target for the British troops to use to mock the young United States.  

The large portrait was in the state dining room. While some accounts suggest Mrs. Madison ordered it cut from its frame,  in fact, she had it unscrewed from the wall. The frame was broken, and the portrait was nestled carefully in the cart. 

Meanwhile, two gentlemen from New York arrived at the White House to offer their assistance to Mrs. Madison. They were Jacob Barker, a financier, and Robert G. L. De Peyster, a merchant.  Barker and De Peyster stayed at the White House after Mrs. Madison left, first for the safety of Dumbarton House (then owned by Charles Carroll who fetched Dolley in his carriage) and then to Virginia.  Barker and De Peyster collected more items, and visited with President Madison later that day. Barker and De Peyster followed the Army out of Washington, traveling along F Street, NW. They spent the night at the private home of a Maryland farmer, and deposited Washington’s portrait in a local farmer’s barn for the night. 

On August 25, 1814, Barker and De Peyster arrived at the United States Army Headquarters at the Montgomery County Courthouse in Rockville.  On August 26, 1814, Barker and De Peyster continued to Baltimore where they ordered provisions for the United States Army. Mrs. Madison had instructed that the cabinet documents (and the White House silver) be stored at the Bank of Maryland in Baltimore, and presumably Barker and De Peyster completed her instructions. 

In 1792, Folie’s map of Baltimore shows the Bank of Maryland standing at the approximate location of today’s 26 South Street, on the west side of the street, south of Lovely Lane (now Redwood Street).  

However, Lucas’ 1822 map of Baltimore showed the Bank of Maryland on the east side of South Street, and written descriptions state that it “stood in South Street between Walnut Street and Lovely Lane.”  

Regardless of which side of the street the Bank of Maryland stood in 1814, the Bank of Maryland institution collapsed in 1834, and its possible locations on the east and west sides of South Street have been replaced by early twentieth-century bank and office buildings.  

While it is not possible to visit the vault where Presidential papers were kept during the summer of 1814, the story offers a valuable teachable moment on the role of the federal government.  Why did Mrs. Madison choose to send items to the Bank of Maryland?  Location played a part, as Baltimore was relatively close to Washington, and Virginia’s cities were not as established as banking centers.  Also, in 1814, there was no federal bank. The Bank of the United States, which was established in 1791, was opposed by James Madison as unconstitutional; Madison and others, such as Thomas Jefferson, did not think the federal government needed to be involved in banking and that this could be left to the states.   

When the Bank of the United States’ charter expired in 1811, Congress did not renew it. The Bank of Maryland, established in 1784 and opened in 1791, was one of the oldest banks in the country and retained the right to issue bank notes. I have not found any images of the Bank of Maryland other than the cartoon shown above, but perhaps it resembled another early state bank, the Bank of Pennsylvania, which Benjamin Latrobe designed ca. 1790? 

For more information see:

Cote, Richard.  Strength And Honor: The Life Of Dolley Madison. Mt. Pleasant, SC: Corinthian Books, 2005. Available online at www.books.google.com.

Eshelman, Ralph. A Travel Guide to the War of 1812 in the Chesapeake: Eighteen Tours in Maryland, Virginia, and the District of Columbia. Baltimore: JHU Press, 2011. Available online at www.books.google.com.

Scharf, John Thomas. The Chronicles of Baltimore: Being a Complete History of "Baltimore town" and Baltimore City from the Earliest Period to the Present Time. Baltimore: The Turnbull Brothers, 1874.  Available online at www.books.google.com.

Finding Fort Hollingsworth, Part V

The final post in a series about Fort Hollingsworth in Cecil County provided by archaeologist Jim Gibb. Looks like there's more work to be done, as always - if you're interesting in helping out, consider volunteering with ASM, the Archaeological Society of Maryland!

Fort Hollingsworth was one of several vernacular forts erected by locals at the head of the Chesapeake Bay. Where are the other forts and what did they look like? Have they survived the last century's booming land development? The Archeological Society of the Northern Chesapeake—a chapter of the Archeological Society of Maryland—and noted War of 1812 historian Ralph Eshelman have been exploring the site of what we think is Fort Defiance, a small outwork or gun emplacement just downstream of Fort Frederick (the site of which has not been definitively identified).

Could this be the site of Fort Defiance?

The possible site of Fort Defiance is suggested by a circular depression some 4.25 meters, or about 14 feet, in diameter and 2 meters, or about 6 feet, deep, perched at the top of a bluff overlooking the Elk River. Much of the river at this point is shoaled or marsh and the channel of the stream bends westward, virtually to the foot of the bluff.

Shovel tests—holes about a foot and a half in diameter and excavated up to three feet deep—produced some architectural and domestic (kitchenwares) refuse dating to the late 1800s and some 20th-century incinerated trash, probably from the nearby house. Sifting the soil through quarter-inch mesh screens, however, produced no military artifacts. Systematic metal detecting also led to the recovery of 20th-century trash, but nothing that could be attributed to the War of 1812. The lack of finds isn’t surprising: military sites tend to produce very few artifacts, unless they were battlefields on which intense or protracted fighting occurred. No such fighting occurred at Fort Defiance.

Our field crew prepared a preliminary topographic map of the site to document the depression as well as some other curious landforms just 50 feet south of the depression. A road had been cut through the bluff sometime in the late 20th century, probably to afford access to the narrow beach below. That road cut complicates an already irregular, eroded topography and it lies between the circular depression and a narrow ridge that has one of the best…if not the best…view of the Elk River. Could this ridge be an eroded remnant of a gun emplacement?



We can’t tell…not yet, anyway. We will return to the site soon, hopefully with Bill Stephens who has the equipment and skills to produce a topographic map that provides the kind of detail that we will need to sort out the complicated contours.

That brings our series on Fort Hollingsworth to a close, for now...as usual, the more answers you find, the more questions those answers generate.

Finding Fort Hollingsworth, Part IV

Today we're pleased to bring you the fourth entry in a five-part series by Jim Gibb detailing the search for (and discovery of!) Fort Hollingsworth in Cecil County, Maryland...enjoy!

Where was Fort Hollingsworth? What did it look like and what happened to it after the war? These are questions investigated by the Archeological Society of Maryland in 2011 and 2012, with one of its chapters—the Archeological Society of the Northern Chesapeake—taking the lead.

The Baltimore Patriot, the local newspaper at the time, provides the only construction details: a semicircular breastwork approximately 300 feet long with a ditch large enough to accommodate 500 soldiers. The reminiscences of Thomas J. Sample in 1880 and the name of the fort—Fort Hollingsworth—place the fortification on Zebulon Hollingsworth’s farm at the confluence of the Big Elk and Little Elk creeks, just south of Elkton. The Hollingsworth farmhouse and surrounding fields were acquired by the Town of Elkton and the Historic Elk Landing Foundation restored the house as a museum.

Hollingsworth House

The State of Maryland holds an historic easement on the property and has prohibited intensive archaeological investigation, allowing only limited studies to assist the Maryland Historical Trust in managing the site’s archaeological resources.

Since the local archaeology chapter was interested in securing permission from the Trust to hold the Society’s annual field session in archaeology at Elk Landing, they commissioned Peter Quantock, then a master’s student at the University of Denver, to conduct a magnetometer survey of the lawn between the Hollingsworth House and the now wooded marsh to the south. The mapped magnetic anomalies suggested a linear feature—possibly the fortification—beneath the seemingly level lawn.

The magnetometer survey in progress.

Anomalies beneath the surface!

A local firm, Stephens Environmental Consulting, conducted a detailed topographic survey of the lawn in March 2012. The resulting map revealed subtle variations in the topography that matched the magnetic anomalies. Bill Stephens and I then tested the property with a 4-inch diameter bucket auger capable of recovering soil samples from 12 feet and more below the ground surface. We found an area in which soils typical of those from two to three feet deep across most of the lawn and adjacent cornfield appeared just one-foot below grade.

Subtle variations in the topography

All evidence pointed to our having found the fort. To hedge our bets, the Society commissioned Peter Quantock to return to the site, this time armed with ground-penetrating radar, courtesy of Dr. Larry Conyers, his advisor at University of Denver. This survey, also conducted in March 2012, covered the same ground over which Peter had run the magnetometer. The machine emitted energy pulses into the ground and measured the time and intensity of the return signal…much as conventional radar works in the tracking of aircraft and ships. The resulting map showed a well defined anomaly…a linear pattern of strong, rapid return signals…that corresponded with the magnetic anomaly, the surface contours, and the soil anomalies. We found the fort!

The radar imagery that identified Fort Hollingsworth!

Of course, finding the fort and proving that we found the fort are not quite the same thing. We finally persuaded a skeptical Maryland Historical Trust to allow us to conduct test excavations to prove that we had found the trench. Permission granted…provided we excavated no more than forty square meters, less than 400 square feet, or an area a little larger than my home office. We did it in twenty-eight square meters. The Society’s field session crew excavated a nearly contiguous line of fourteen units, each measuring one meter by two meters, or about 3 ft by 6 ft, extending from well south of where we thought the ditch was located to a point well within the presumed fort interior.

Unit 1 was the southernmost unit, Unit 3 the northernmost, and Unit 2 was placed where we thought the ditch was located. Unit 2 came down on the ditch and the intervening eleven additional units provided a single trench in which we could clearly see the full width of the ditch. Nothing but scattered gravels remained of the earthwork in this portion of the fort.

With this bit of ‘ground-truthing’ it is possible to reevaluate the radar data and, using the survey data collected by Bill Stephens, to accurately stake the ditch on the ground. Future excavations, if permitted, should reveal remnants of the earthwork and, possibly, gun emplacements and evidence of militia bivouacs. The portion of the ditch that we excavated revealed that the fort was demolished simply by shoveling the earthwork back into the ditch, sometime after February 1815. The land reverted to cultivation. And so we achieved our goals of finding and documenting Fort Hollingsworth. Additional radar and excavation could reveal internal structure of the fort, such as gun emplacements and militia camps. But we don’t know how it compares with other forts built by citizens at the same time…that will require finding and investigating those sites. More about that in the next post!

Finding Fort Hollingsworth: Part III

Jim Gibb continues the story of Fort Hollingsworth in this third post in a series about the discovery and exploration of this Cecil County fort...

It wasn’t until the spring of 1814 that the British attempted a landing at Elkton, and just eleven ‘guns,’ or rounds fired, from the fort discouraged the effort:

Five barges were discovered on the [Elk] river and about one o’clock they opened upon our view from behind a point, and point blank shot, say ½ a mile. We gave them in all eleven guns, so well directed, that they hastily put about and retreated down the river having fired but three at us, which did us no injury (Gen. T. M. Forman to Martha Ogle Forman, 12 July 1814; quoted in Eshelman et al., 2010: 111).

The 1814 season was the most devastating part of the two and a half year war for the people of the Chesapeake region. British attacks became more common, more destructive, and more audacious. One British officer characterized Admiral Cochrane’s attacks on Havre de Grace and other settlements on the upper portion of the Bay as devoid of tactics. Plans were rudimentary and the strikes opportunistic. Their tenor was that of punishment for affronts to the dignity of the King and his Navy, the excessive and uncontrolled anger of an abusive parent. British plans to use the Upper Bay in an attack on Philadelphia, if ever seriously considered by the Admiralty, were abandoned. The British Navy sought to punish and to encourage the United States to settle a treaty as quickly as possible.

When the British marines rounded Cedar Point in the early afternoon, the defenders of Fort Hollingsworth likely knew of their approach from militia patrols along the lower portion of the Elk River. Arrogantly, the attackers approached the fort in daylight, without benefit of surprise. And they were met by eleven guns—which is to say, they were fired upon by the militia eleven times (not by eleven cannons). They responded with three cannon shots, but retreated: an attack would have yielded too many casualties and uncertain rewards.

When word of the treaty between the USA and Great Britain reached Maryland in February 1815, the people of Cecil County celebrated at Fort Hollingsworth. From then on the historical record is silent with the exception of the reminiscences of an elderly judge in Ohio published in the Cecil Whig in the 1880s, recounting his experiences at age 14. The fort was abandoned and, presumably, demolished.

More to come...

Finding Fort Hollingsworth: Part II

We now bring you Part II of our ongoing series of blogs by Jim Gibb about the archaeological project to locate Fort Hollingsworth, near Elkton, MD.

The Baltimore Patriot newspaper reported measures undertaken by the people of Elkton and the surrounding countryside at the onset of the 1813 fighting season:

[A] meeting of the people of the town [Elkton] and county [Cecil] was called, when not less than 200 convened at the court-house, and in a few minutes $1,000 was raised; a committee of three appointed; and on Saturday the ground laid out for three breast-works; one at Elk Landing [Fort Hollingsworth], one between the landing and Frenchtown, and one at Frenchtown. On Saturday [April 17, 1813] the first was nearly completed—300 feet of a semi-circle; and mounts five 6-pound cannon; the trench sufficient to contain 500 (Baltimore Patriot, 22 April 1813; quoted in Eshelman et al., 2010: 110, 112).

This brief news item brims with historical information. First, the people at the head of the Bay organized their own defense. This wasn’t an undertaking of the national or state governments, or even of county government. Local folks, purchased their own arms, contributed funds for the purchase of cannons, powder, and shot, and built their own forts. There is no evidence of regular army involvement, and the people of Cecil County appear to have built the three forts without the benefit of trained, experienced military engineers.

When the United States declared war in 1812, it was the first time since the Battle of Yorktown—the last major conflict of the American Revolution—that the nation fought a ground war. Militias in the Northwest Territories and the Southeast battled Indian nations and President Washington led regular troops into Western Pennsylvania to quash the Whiskey Rebellion; but for thirty years the United States had only a very small trained ground force and only a nascent military academy at West Point (established 1802) for training officers and engineers.

The people of Cecil County, possibly informed by reading military works of classical antiquity, or perhaps even 18th-century French and English works on the proper conduct of warfare, largely relied on native intelligence and their knowledge of British tactics and local geography. The fortifications that they built, unlike the grand Fort McHenry in Baltimore, are best seen as vernacular architecture: products of local traditions informed to a greater or lesser extent by academic writings.

Even the contributor to the Baltimore Patriot, in the quotation above, betrays a hazy sense of fortifications and how they work when he stated that the trench was “sufficient to contain 500.” The trench was a source of material for constructing the breastwork, but its role—apart from providing soil for the earthwork—was that of a dry moat; an obstacle for attackers to overcome. Placing infantry outside of the earthwork and into the trench would hinder their retreat, if necessary, and they would have fire-belching cannons discharging over their heads. The trench might well have fit 500 men, but that was not how it functioned.

On the earthwork the defenders placed five cannons that fired six-pound solid shot. Although light and maneuverable, these were not imposing guns. In contrast, American gunboats of the time were designed to carry 18- and 24-pounders.


 In the end, however, the size guns mounted on fortifications and gunboats depended on what could be procured from the foundry near the mouth of the Susquehanna River (across from Havre de Grace, just east of Perryville), furnished by visiting militia and flotilla-men, or captured from the enemy. Those five guns were fired at British marines during the only engagement in which Fort Hollingsworth participated, the subject of the next post...

Finding Fort Hollingsworth - Part I

This is the first in a series of posts that will share the discovery of Fort Hollingsworth at Elk Landing in Cecil County. The location of Fort Hollingsworth has been known (or at least suspected) for many years, but prior to this project, no evidence of the fort's remains, of its shape and configuration, had ever been found.

X Marks the Spot

In all likelihood, unless you hail from Cecil County, Maryland, and/or are a history buff, you don't know much about Fort Hollingsworth. So, let's start with some background. I shall now turn you over to archeologist Jim Gibb, who has generously provided us with this interesting series of posts...

Part I

The British navy began raiding public landings in the late summer of 1812, soon after the US Congress issued its declaration of war against Great Britain. The Admiralty used these raids as part of a strategy to coax American regular army troops off of the Canadian frontier (documented in a letter from Lord Bathurst, secretary for War and the Colonies, to Colonel Sir Thomas Beckwith of the British Army, dated March 20, 1813; also a letter from Vice-Admiral Cochrane of the Atlantic Squadron to Canada’s Governor-General Sir George Prevost, dated March 11, 1814). But British tactics turned to revenge when Canadian towns burned and British citizens faced winter weather without food, clothing, and shelter (documented in a letter from Admiral Cochrane to Rear Admiral Cockburn dated April 28, 1814). Beginning in the spring of 1814 and increasing in ferocity throughout the rest of that year, British marines looted and burned not just public facilities, but plantations and small towns along the Chesapeake’s coastline. Raiders used the slightest provocation to justify destruction of private properties throughout the Bay region. Most of their attacks occurred during the spring through late autumn, part of the British fleet retiring to Bermuda for the winter while individual vessels cruised the Atlantic or blockaded the Bay.

A current USGS Topo Quad showing critical locations of all this drama

When British marines attacked, they did so without warning, setting out from their ships in large boats, or barges, landing at a plantation, public wharf, or town at dawn. In part because of surprise, but also because the region was inadequately defended, the attackers met with little resistance, and any resistance served as justification for theft and destruction of the property of non-combatants. (For years after the war, citizens sought restitution from the US Congress.) If militia responded, they generally arrived too late, the marines having rowed back to their ships.  One can envision a ‘Keystone Cop’ scenario, militia rushing from one attack site to the next, always too late and too feeble to have protected citizens and their property.

There was nothing comical about loss of farms, stores, and tobacco awaiting shipment, or of the occasional loss of life. But even more serious was a plan considered by the British Admiralty in which they would use a pincer movement to attack Philadelphia, one of the new nation’s largest and commercially most important cities. One prong would be a ship-borne invasion force arriving via the Delaware Bay and River; the other an overland march from Elkton after British marines secured the town (Letter of Admiral Cockburn to Admiral Cochrane dated July 17, 1814). The burning of Frenchtown, just downriver from Elkton, and of Havre de Grace on the Bay, showed what British forces were willing to do -and capable of doing. Despite the vulnerability of the Bay and of the cities of Baltimore and Philadelphia, the central government provided few resources with which to defend the region; a decision that led to the burning of the national capital in 1814.

Marylanders, often without any kind of federal aid, defended themselves, raising and equipping militia, and planning and building defensive works, particularly in the upper part of the Bay. The people of Cecil County were exceptional in this regard, and it is their story that the Archeological Society of Maryland is researching and writing and that I address in the next blog.

More to come! Stay tuned...