Overview
Iris and Mercury were fast Royal Navy despatch vessels later categorized as second-class protected cruisers.
Developed for Royal Navy, Iris class belongs to the Cruisers family and is associated with Late 19th century. Its documented designations include Despatch vessel and Second-class protected cruiser, while its intended roles include Scouting and Dispatch.
Development and construction
Their 1875 building specification records a paired design at a time when cruiser construction was moving toward steel hulls and steam-first performance.
The documented program for Iris class lists 2 planned, 2 ordered, 2 laid down, 2 completed, and 0 cancelled, with design work beginning in 1875, construction beginning in 1875, and construction ending in 1878. These figures define the scale and chronology currently supported by the class sources.
Design characteristics and intended role
The surviving classification data associates Iris class with Steel hull and Steam. Read together with the recorded roles of Scouting and Dispatch, these attributes show the operational problem the design was intended to address without implying specifications that the sources do not establish.
The class record identifies Royal Navy as the principal design or service authority. Where individual ships changed navy, name, or pennant, those later identities are retained on the ship pages rather than treated as separate vessels.
Service history and class roster
The class served in the communications and cruiser roles that were becoming increasingly important to a global navy.
The class roster currently links 2 ships. Named members include HMS Iris and HMS Mercury. The linked ships are associated with Royal Navy.
Historical significance
The Iris class helps connect the older cruising frigate tradition with the protected cruiser lineage of the late nineteenth century.
Iris class is most useful when read as both a design and a group of individual careers. The class page establishes the shared technical and operational context; the linked ship pages preserve differences in construction, service identity, deployment, transfer, preservation, and fate where those details are documented.
Ships in this class
Showing 2 recorded class members.
Sources and further reading
- Specifications for Iris (1877) and Mercury (1878) ↗Royal Museums Greenwich · accessed 2026-09-18
- British War Vessels Photograph Book — Admiralty Intelligence Department, March 1892 ↗Royal Museums Greenwich · accessed 2026-09-18