The fort changed hands several times. Shortly after his arrival to take up his position as up as
Director-General of New Netherland in 1647,
Peter Stuyvesant, attempted to re-assert control of the region and its lucrative trade. In his initial attempt at control, he effected the construction of
Fort Beversreede near the terminus of the
Great Minquas Path, at the mouth of the
Schuylkill. The location of earlier-built
Fort Nassau on the east bank (now
New Jersey) of the river, had proved disadvantageous since the richest fur-trapping area of the native
Susquehannock and
Lenape populations was inland to the west. In 1651, Stuyvesant had the fort dismantled and relocated to the western bank downstream from
Fort Christina, the first and one of the larger Swedish settlements. He named it Fort Casimir. Fort Beversreede was abandoned and the Dutch presence was consolidated. On
Trinity Sunday in 1654,
Johan Risingh, Commissary and Councilor to
New Sweden Governor Lt. Col.
Johan Printz, officially assumed his duties and his attempts to expel the Dutch from the
Delaware Valley. Fort Casimir surrendered to the Swedes and was renamed Fort Trinity (in Swedish
Fort Trefaldighet). On June 21, 1654, the native peoples met with the Swedes to reaffirm their alliance. Stuyvesant led a Dutch force which retook the fort on September 11, 1655, renaming it
New Amstel (in Dutch
Nieuw Amstel). Fort Christina, located to the north fell on September 15, 1655.
Fort Nya Elfsborg, on the east bank, was abandoned and set afire by departing Swedish forces.
New Sweden came under the control of the Dutch. John Paul Jacquet was immediately appointed vice director, making New Amstel a regional stronghold of the Dutch colony, subordinate to
New Amsterdam. It has been suggested that the
Peach War attack was a retaliation, as the indigenous population considered the treaty with the Swedes to include a defence alliance. In 1664, the Dutch surrendered control of
Fort Amsterdam, and thereafter all of
New Netherland fell to the English. Proceeding south the English peacefully took
Fort Altena. Some resistance was offered at Fort Casimir, but the fort quickly succumbed. In 1673–1674 it came under Dutch control again, but reverted to the English after the signing of the
Treaty of Westminster. The fort was abandoned around 1675 and the site was used for several different commercial purposes. Low laying areas around the old fort site were filled with ash. It is believed that presently a parking lot and several houses are located above the remains of the fort. A preliminary archeological survey of the area was conducted in 1986. ==Name==