[3] Constructed during the Dutch possession of the region, the fort was a vital defensive fortification strategically located at the mouth of the Essequibo River.

In 1726, it was resolved that a fort should be constructed to protect the planters and the interest of the Dutch West India Company (DWIC).

In 1726, Leslorant, an engineer, was sent from the Netherlands to construct a horn work with wooden redoubt and a strong palisade of the northern point of Vlaggeneiland (Flag Island).

In August 1738, Laurens Storm van 's Gravesande, the Secretary to Commander Gleskerk, inspected the fort and reported that the structure was falling to pieces.

Fort Zeelandia consisted of a redoubt of fifty square feet, with walls thick enough to endure the heaviest ordnance.