What was the smallest purpose-built World War I-era carrier intended to operate fighters?
Short answerHMS Hermes fits the wartime design requirement: she was ordered and laid down during World War I as a carrier, though she was completed after the war.
NotesHMS Hermes was ordered in 1917 and laid down in 1918, although she entered service after World War I. Those dates make her a candidate for a purpose-built fleet carrier conceived during the war, rather than a carrier actually available for wartime operations. Hosho was laid down later and completed sooner; Argus and Eagle followed conversion routes. The seaplane tender later called Pegasus was a different kind of aviation ship from Hermes. Hermes's early two-island studies also show how much her layout changed before completion. A full flight deck remained part of the eventual carrier arrangement.