Why the frigate, sloop, and corvette labels need context

Loch, Bay, River, Captain, and earlier escort types share enough visual and technical features to complicate the familiar corvette-to-frigate progression and point back toward the sloop family. Photographs and technical particulars make that lineage more visible than the labels alone. A River-class history is criticized for repeatedly calling the ships corvette developments, although the book is otherwise regarded as excellent. That mixed judgment is useful: a source can remain valuable while one part of its design interpretation is open to challenge. The classification question concerns which earlier ships, construction standards, and operational requirements actually shaped the wartime frigate.