 Large amounts of earth and other necessary materials were brought aboard river barges from the Fort Lillo, located on the Dutch-controlled opposite riverside, which allowed the sappers to build high and wide embankments.William garrisoned half of his troops in those entrenchments, sending the remaining to harass the Forts of Sainte Marie and Verrebroek., from where they were receiving artillery fire and skirmishes were made by the Spanish to regain the levees between Kallo and Sainte Marie.An assault against this fort was rejected by its German garrison on the 17th, although the following day it was abandoned by its defenders and occupied by William's troops.