The fortress at the east side of town was completed in 1861 and together with the fortifications of Weesp was part of the New Dutch Waterline defences. In 1892 it was transferred to the Amsterdam Defence Line. It is one of the last tower forts used in the Waterline. With the introduction of the explosive grenade, the fort with its brick walls became extremely vulnerable.
The fort, with its original wooden engineers shed, was mobilised twice, during 1870-1871 (French-German war) and in 1914-1918 (World War One).