With sister ship , "O 15" attended the Brussels International Exposition in 1935. During the Spanish Civil War "O 15" was on convoy duty, from 23 March to 24 June 1937, protecting Dutch merchant ships. On 2 October 1939, the ship left with and the sloop for Curaçao, via the long route (around Scotland) because of the threat of mines in the English Channel. After 27 days the ship arrived in Curaçao on 29 October.