few houses and invested in the import of Norwegian timber piles and real estate, which was intended for shipwharves. He is also said to have designed the church in Hoogeveen. In 1658 he had bought a small country estate in Sauwerd. Without being completely relieved of his duties in the Netherlands, Ruse went on to realise various fortification assignments for John Maurice, Prince of Nassau-Siegen, including the huge citadel at Kalkar, and for Christian Louis, Duke of Brunswick-Lüneburg, the most important of which was the fortification of Harburg in 1660. Danish assignments After the peace treaty at the end of the Second Northern War in 1660, Frederick III of Denmark commissioned Ruse to reconstruct the damaged fortifications of Copenhagen. In 1661, he was appointed quartermaster general, chief inspector of fortifications and colonel of an infantry regiment. Ruse immediately submitted a plan for rebuilding the Copenhagen citadel which was accepted. Construction work, completed three years later, caused some bitterness among the local citizens, leading as far as threats to Ruse's life. In 1667, Ruse also completed the defences of Frederiksort in the Duchy of Schleswig. He travelled around Denmark, inspecting and repairing the defences, especially those in Kronborg, Nyborg and Fredericia. Thereafter he was involved in large-scale civil construction work in Copenhagen including cemeteries and monuments including the one to Corfitz Ulfeldt. But above all, he drew up plans for two new districts, one to the northeast of Kongens Nytorv and Gothersgade (Frederiksstaden) which included the Nyhavn Canal, the other southwest of Slotsholmen (Frederiksholm). In 1664, Ruse was appointed major general and member of the war cabinet. With the threat of war with England, he was sent to Norway together with Frederik Ahlefeldt in 1667. In 1669, he became commander of Fredericia and, in 1671, commander in chief responsible for fortifications in the duchies. From 1667 to 1670, he also coordinated significant extensions to the Copenhagen and Christianshavn ramparts. His next major work, during the last year of Frederick III's reign, was the rebuilding of the fortifications at Rendsburg in Schleswig. Ruse justified his efforts explaining that Denmark needed to be protected from the south, with additional defences in Sonderburg and Friedrichsort on the western shore of Kiel Fjord. In this way, the entire area could be systematically defended. He had hoped to undertake a much more extensive project on both sides of the River Eider but this was hampered by