[1] de Raet had already worked on similar projects in Spain and Italy, such as draining 1,600 hectares of a lake at Massaciuccoli in the Republic of Lucca, for which he had purpose-designed a new device.
Julius was unable to get the state council to finance his projects and so in 1575 he signed a contract with de Raet making him his personal "master builder on water and on land" and requiring de Raet to spend three months of each year in Wolfenbüttel and to found a company to construct and operate the planned canal between the Harz and the North Sea.
Rudolf II, Holy Roman Emperor passed a decree putting an end to the project, but even so de Raet continued and enough of it was completed to enable the drawing of rafts to Wolfenbüttel on the Oker and Nette.
He attempted to replace it with a plan to link the Oker to the Aller via the Aue, Erse and Fuhse, but this was successfully opposed by William the Younger, Duke of Brunswick-Lüneburg.
[3] de Raet was also put in charge of regulating the flow of the Oker and Innerste south of Wolfenbüttel in Richtung towards the Harz, which he carried out from 1574 to 1577.