in 1663 adelaer had begun working as an agent for the danish navy, that in this period had close ties with the dutch navy. the leading dutch military advisors in denmark, including frederick stachouwer and volckert schram, were recalled to the dutch republic because of their expertise in amphibious landings, to be employed in a planned landing on the english coast which in 1667 materialised as the raid on the medway. subsequently, adelaer was asked to join the danish navy as operational supreme commander, to supervise the modernisation of their fleet. in 1666 king frederick iii of denmark personally convinced adelaer by offering him a considerable commission. while in the dutch navy any commoner could be appointed in the highest positions, in denmark it was still mandatory to be of nobility to command, so adelaer became the danish knight "coort sifvertsen adelaer" in order to become admiral-general.