A promising experiment became a procurement failure

Roger Keyes, David Beatty, and John Jellicoe supported the fleet-submarine idea, while Jackie Fisher opposed putting oil-fired steam machinery into submarines. Their enthusiasm reflected the genuine tactical attraction of a hidden weapon able to accompany the battle fleet. Testing one or two boats was a defensible experiment, but ordering twenty-one vessels multiplied the unresolved hazards. The design dated from 1913, before wartime urgency could excuse committing to production without fuller operational proof. The criticism concerns the scale and timing of procurement rather than experimentation itself.