A Bittern-class survey assignment on the China Station shows how peaceful hydrographic work could also improve situational awareness in a tense region. The Egret and Black Swan classes reveal the accumulating escort lessons of the interwar programme. Black Swans remained well below the treaty's upper displacement threshold, making them practical for more yards and less directly comparable with destroyer construction. Their wartime gun, radar, depth-charge, and mortar fits made the class a major anti-submarine force.
Chapter · 58:18-1:02:26
From Bittern surveys to Black Swan escorts
Later interwar sloop classes combined surveying and intelligence-gathering duties with an increasingly clear path toward specialist anti-submarine escorts.