On 1 July 1639 he was appointed commander of Fort Christina in New Sweden and left Gothenburg on the ship Kalmar Nyckel in September 1639.
Upon arrival Ridder wrote back to Sweden to Admiral Claes Fleming and Chancellor Axel Oxenstierna requesting more colonists and skilled workmen.
This request was fulfilled when Kalmar Nyckel and Charitas arrived to the settlement on November 7, 1641 with additional settlers including many Forest Finns.
In February 1659 Ridder took part in the fleet's attempt to capture Copenhagen during the Second Danish War, during this operation he was wounded.
During the autumn, he then led a naval force that maintained the connection with Stettin in Swedish Pomerania, which was besieged by Brandenburg and Austria.