Fort Casimir: The Beginnings of New Castle

Originally called Fort Casimir under Dutch rule, when New Sweden took possession, the Fort was briefly re-named Fort Trinity.

Courtesy of the New Castle Historical Society

Early Dutch Settlement and Fort Casimir

In 1651, the Dutch built Fort Casimir to control access to land they had claimed earlier in the century. This fort marked the beginning of what would become the City of New Castle. Throughout the seventeenth century, European powers competed to expand their influence by opening trade routes to the Americas, lands they had only recently realized existed. Along the northern East Coast of what is now the United States, the fur trade with Indigenous Peoples proved especially lucrative. By the mid-seventeenth century, Dutch, Swedish, and English settlers and traders all had a presence in the region.

Dutch Exploration and the Naming of Sandhoek

Henry Hudson, an Englishman sailing for the Dutch, noted Delaware Bay in 1609 during his exploration of the East Coast. In 1621, the Dutch West India Company established the colony of New Netherland to capitalize on fur trading opportunities. The colony stretched from the South River (the Delaware River) to the North River (the Hudson River) and the Fresh River (the Connecticut River). When Dutch explorers entered the bay and traveled the South River, they named the point that would later become New Castle “Sandhoek,” meaning Sand Hook or Sand Point.

Map made by Claes Janszoon Visscher in 1651 depicting the New Sweden.

Courtesy of the New Castle Historical Society.

Swedish Expansion Along the South River

The Dutch concentrated most of their efforts farther north, building their main trading post on the North River at New Amsterdam, now Manhattan. Because the Dutch were rarely present along the South River, the Swedes took advantage of the situation. In 1638, the Swedes built Fort Christina in present-day Wilmington, naming it after their queen. Swedish colonists farmed the surrounding land and traded with the Lenape people.

Dutch Response: Construction of Fort Casimir

In response, Peter Stuyvesant, the director-general of New Netherland, ordered the construction of Fort Casimir at Sandhoek, downriver from Fort Christina. Its location allowed the Dutch to control traffic along the river and access to the bay and Atlantic Ocean. Stuyvesant hoped the fort would help reassert Dutch authority in the region.

Structure and Layout of Fort Casimir

Fort Casimir stood near what is now the intersection of Second Street and Chestnut Street in New Castle. Although no visible remains of the fort survive today, archaeological evidence and historical accounts suggest it was constructed with timber curtain walls, earthen ramparts, and a surrounding ditch or moat, which may have been dry or filled with water. Bastions at each corner provided defensive positions for cannon fire. Inside the fort were wooden buildings that housed soldiers and stored food, weapons, munitions, and supplies. After leaving a garrison at Fort Casimir, Stuyvesant returned to New Amsterdam.

Swedish Capture and Fort Trinity

In 1654, Swedish forces marched south from New Sweden to Fort Casimir, which had fallen into disrepair. Seeking to reestablish their influence and trade relationships with the Lenape, the Swedes easily outnumbered the Dutch garrison, which surrendered without resistance. The Swedes rebuilt the fort, renamed it Fort Trinity, and added a wall along the river armed with six cannons.

Map created by Peter Lindström in 1654 of New Sweden

Courtesy of the New Castle Historical Society

Dutch Recapture and Renaming to New Amstel

The following year, in 1655, the Dutch West India Company recaptured the fort with a force of 300 men. Burdened by heavy debts to the City of Amsterdam, the Company turned the fort and surrounding settlement over to the city in 1657 as partial payment. The settlement was renamed New Amstel. Jacob Alrichs, Director of New Amstel, ordered repairs to the fort and construction of new buildings both inside and around it.

English Seizure of New Netherland

In 1664, English forces seized control of the New Netherland colony on behalf of James Stuart, the Duke of York and brother of King Charles II. The fort at New Amstel was undermanned, and its defense depended largely on local militia. Under the leadership of Robert Carr, English forces persuaded local residents to remain neutral and attacked the fort from both the river and land. After less than an hour of fighting, the English emerged victorious without suffering casualties, while three Dutch soldiers were killed and ten wounded.

Carr then seized and plundered the settlement and claimed lands along the river as far south as present-day Lewes, granting property to his men. The former New Netherland colony remained under English control until the American Revolution.

Decline and Archaeological Investigations

By the 1670s, Fort Casimir had fallen into ruin. A fortified blockhouse was built on The Green to replace it, and the original fort lot was sold with the condition that the remaining structures be demolished.

Archaeologists have investigated the site several times since 1986, uncovering evidence of fort structures, interior buildings, and artifacts that provide insight into daily life in the seventeenth century. The most recent archaeological investigation, conducted in 2019, was funded by a grant from the National Park Service’s American Battlefield Protection Program.

Historic Benchmarks

This article is part of a series titled Historic Benchmarks: New Castle and the Making of a Nation which was created in partnership with the Delaware250, New Castle Historical Society, Old New Castle Outdoor Recreation Coalition, the City of New Castle, and The Trustees of the New Common.

References

Benson, B. E., & Hoffecker, C. E. (2021). New Castle, Delaware: A Walk Through Time. New Castle, Delaware: Oak Knoll Press.

Cooper, A. B. (2020). The History of New Castle, Delaware. (J. Meek, Ed., & J. Meek, Trans.) New Castle, Delaware: New Castle Historical Society and Oak Knoll Book.

Higgins, A. (Ed.). (1973). New Castle on the Delaware (Third ed.). New Castle, Delaware: New Castle Historical Society.