5 Must-See Historic Forts In Delaware

Delaware may be small, but it is rich in military history. Fort Delaware on Pea Patch Island defended the ports of Wilmington and Philadelphia and later served as a Union prison during the Civil War. Across the river, Fort DuPont helped protect the region and now offers scenic trails and picnic spots along the Delaware River. Along the Atlantic coast, Fort Miles defended vital ports, and today, it features restored bunkers at Cape Henlopen State Park. Earlier history can be explored at Fort Christina, the landing site of Swedish settlers, while Fort Casimir’s story lives on in New Castle’s historic district. Together, these must-see forts provide a tangible connection to Delaware’s role in shaping the nation.

Fort Delaware

Fort Delaware sits on Pea Patch Island in the Delaware River, straddling Delaware and New Jersey. Completed in 1859 to protect the ports of Wilmington and Philadelphia, it later served as a Union prison during the Civil War, at one point holding more than 10,000 Confederate soldiers. The fort saw brief use in both World Wars before being abandoned in 1944 and becoming a state park in 1951.

Today, Fort Delaware State Park brings history to life. While there, explore the fort with costumed interpreters, watch demonstrations of 19th-century military life, attend seasonal reenactments, or even join paranormal tours. The park is accessible by ferry from Delaware City or Fort Mott State Park and is open seasonally from late April through September and on select holidays.

Fort DuPont

Located just south of Delaware City, Fort DuPont was established in 1863 as the Ten Gun Battery, built opposite Fort Delaware to strengthen the region’s defenses. Named for Civil War Naval hero Rear Admiral Samuel Francis Du Pont, the fort protected key port cities with rifle, mortar, and rapid-fire batteries, some of which remain visible today. Over the years, its role shifted from active coastal defense to training, and during World War II, it even served as a prisoner of war camp. A theater built in the 1930s also still stands, offering a glimpse into the fort’s mid-20th-century life.

Today, Fort DuPont is part of Fort DuPont State Park, located along the Delaware River and the Chesapeake & Delaware Canal. The park combines history with outdoor recreation, featuring the Rivertrail Trail, which loops past three historic military batteries and scenic picnic spots along the river, perfect for birdwatching and exploring the fort’s storied past. The park is open year-round, with a small vehicle entrance fee.

Fort Miles

Perched on a high bank overlooking the Atlantic Ocean, Fort Miles was established in 1941 as part of the Harbor Defenses of the Delaware. During World War II, more than 2,300 soldiers manned its massive guns, minefields, and searchlights to protect Wilmington, Philadelphia, and other vital trade centers from potential naval attacks. It's underground and above-ground batteries, along with fire control towers and barracks, were built to defend against enemy ships, while the Cold War later brought highly classified missions, including weapons development and submarine detection.

Fort Miles is now home to the Fort Miles Museum and Historical Area, within Cape Henlopen State Park, which features restored bunkers, artillery batteries, the fire control tower, and the Fort Miles Artillery Park. Exhibits and hands-on displays offer a glimpse into the daily life of the soldiers stationed there and the fort’s strategic role in coastal defense. The museum’s hours vary by season, so be sure to check before planning a visit.

Fort Christina

Located in Wilmington, Fort Christina marks the historic landing site of Swedish settlers in 1638, who established the colony of New Sweden. This early settlement played a key role in shaping the colonial history of the Delaware Valley and the future United States. The site later became part of Delaware’s First State National Historical Park. A centerpiece of the park is the Swedish Tercentenary Monument, a gift from Sweden commemorating the 300th anniversary of the colony and honoring the lasting ties between Sweden and the region.

To learn more about the park's cultural and historical significance, guided tours are available from Memorial Day through October. While visiting Fort Christina itself is free, small fees apply for tours at the nearby Old Swedes Historic Site and through the Kalmar Nyckel Foundation.

Fort Casimir

Built by the Dutch in 1651 in what is now New Castle, Fort Casimir quickly became a flashpoint in the struggle for control of the Delaware River. A few years later, Swedish settlers from nearby Fort Christina captured it and renamed it Fort Trefaldighet, or Fort Trinity. By 1655, Peter Stuyvesant, a Dutch colonial governor, had reclaimed the fort, only for it to later fall into English hands in 1664. Its capture secured English dominance over the Delaware Valley and marked the end of the region’s short-lived New Sweden colony.

Although the original fort is no longer standing, the site is located within New Castle’s historic district, where preserved colonial-era buildings reflect the area’s role in early European settlement. The location highlights the colonial rivalries that shaped the Delaware Valley in the 17th century.

Discovering A Piece of Delaware's History

From Civil War prisons to World War II coastal defenses, Delaware’s historic forts offer insight into the state’s past. Today, they are preserved as museums and state parks, where scenic trails, restored buildings, and interactive exhibits bring history to life. Walking through Fort Delaware’s grounds, exploring the scenic Rivertrail Trail at Fort DuPont, or touring the bunkers and artillery at Fort Miles allows a direct connection to the people, strategies, and events that shaped the Delaware Valley. These forts provide a unique opportunity to step back in time and experience the stories that helped shape the nation.