The redoubt Utrecht, built on a high sand dune to the south of Fort Zeelandia, was a supporting fortification meant to prevent the dune from being taken in case of a siege, as the dune might be used to fire into the fort. During the siege of fort Zeelandia by the Chinese warlord Koxinga in 1661-1662 there was fierce fighting for the redoubt, and it was finally taken on the night of the 25th of January 1662. This left the besieged in Fort Zeelandia in a hopeless position, and negotiations for the surrender of the fort commenced two days later.
