Mattapany-Sewall Archeological Site
An archaeological site in Maryland associated with a seventeenth-century plantation, colonial administration, and the 1689 overthrow of Maryland's proprietary government.
Last updated August 26, 2026
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Overview
The Mattapany-Sewall Archeological Site is a historic archaeological property in St. Mary's County, Maryland, on the grounds of Patuxent River Naval Air Station. It occupies a relatively level terrace roughly 45 feet above sea level and less than 1,000 feet from the Patuxent River. The site is situated in an unused wooded and grassy area, where archaeological remains and documentary evidence identify the location as Mattapany-Sewall, a colonial manor established in 1663. The property is associated especially with Charles Calvert, 3rd Baron Baltimore, the proprietor of the Maryland colony. Documentary records indicate that Calvert occupied the manor from 1666 until 1684. During this period, Mattapany-Sewall was more than a private plantation residence. It functioned as a governmental meeting place and as a colonial arsenal, reflecting the overlapping domestic, administrative, and military roles of prominent seventeenth-century estates in proprietary Maryland. The site also became connected with the Protestant Revolution of 1689, an uprising that ended the authority of Maryland's Catholic proprietary government and transferred control of the colony to the Crown. Mattapany-Sewall was the scene of the battle associated with that change in power. This connection gives the site importance beyond its architectural or plantation history: it is also a place tied to political conflict, religious tension, and the transformation of Maryland's colonial government. Because the subject is an archaeological site rather than a commercial brand, there are no known products, consumer offerings, corporate executives, financial results, or commercial operating markets to document. Its significance lies in the archaeological record, its relationship to colonial Maryland, and its association with Charles Calvert and the events of 1689. The property was listed on the United States National Register of Historic Places in 1985. Additional documentation is held by the Maryland Historical Trust, and the Historic American Buildings Survey recorded the site under the title “Mattapany” in a set of photographs and supplemental materials.
History
Mattapany-Sewall was a colonial manor in St. Mary's County, Maryland, established in 1663. The site is located on a terrace near the Patuxent River, within what is now Patuxent River Naval Air Station. Its position near the river would have provided access to transportation and communication routes that were important to colonial settlement and administration. The manor's principal historical association is with Charles Calvert, 3rd Baron Baltimore, proprietor of Maryland. Documentary evidence indicates that Calvert occupied Mattapany-Sewall between 1666 and 1684. In proprietary Maryland, the residences of leading officials could serve several functions at once. Mattapany-Sewall operated as a manor and plantation while also providing a setting for governmental meetings. It was additionally used as a colonial arsenal, giving the property an administrative and defensive role. The site later figured in the political crisis known as the Protestant Revolution of 1689. Maryland's proprietary government, led by the Catholic Calvert family, faced opposition from Protestant colonists amid broader disputes over religion, political authority, and the colony's relationship with the English Crown. The conflict culminated in the overthrow of the proprietary government. A battle connected with that uprising took place at Mattapany-Sewall, making the property a physical setting for a major transition in Maryland's colonial political order. After its period of direct association with Calvert and the proprietary administration, the property became important primarily as an archaeological resource. The surviving landscape and subsurface evidence offer a basis for studying the material conditions of a seventeenth-century Maryland manor, including its residential, governmental, and military uses. The site is located on an approximately level terrace about 45 feet above sea level and under 1,000 feet south of the Patuxent River, in a wooded and grassy tract that is not used for ordinary development. Mattapany-Sewall was placed on the National Register of Historic Places in 1985. It has also been documented by the Maryland Historical Trust and by the Historic American Buildings Survey, which recorded the property as “Mattapany” in HABS No. MD-688. The HABS documentation includes photographs and supplementary material. In historical terms, the site is significant because it brings together the study of colonial plantation life, proprietary administration, early military organization, and the political upheaval that ended Maryland's proprietary regime.
- 1985
National Register of Historic Places listing
[1]The site was added to the United States National Register of Historic Places.
- 1689
Battle during the Protestant Revolution
[1]Mattapany-Sewall was the scene of a battle associated with the Protestant Revolution that overthrew Maryland's proprietary government.
- 1684
End of Calvert's documented occupation
[1]The documented period during which Charles Calvert occupied Mattapany-Sewall ended in 1684.
- 1666
Charles Calvert begins occupying the manor
[1]Charles Calvert, 3rd Baron Baltimore, is documented as occupying Mattapany-Sewall from this year.
- 1663
Mattapany-Sewall manor established
[1]Documentary evidence places the establishment of the colonial manor at Mattapany-Sewall in 1663.
Products and positioning
A historically significant archaeological and heritage site documenting seventeenth-century colonial Maryland, proprietary government, plantation life, and the 1689 Protestant Revolution.
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