What would replace Invincible, Indefatigable, and Queen Mary in the Grand Fleet if they were sent to the Dardanelles?
Short answerWhatever capital ship was available, possibly a Queen Elizabeth-class unit, unless earlier construction had enlarged the fleet.
NotesSending Invincible, Indefatigable, and Queen Mary to the Dardanelles would leave the Grand Fleet with whatever capital ships remained available. The counterfactual cannot add ships to the Royal Navy's finite force, so a Queen Elizabeth-class ship or another unit might occupy the vacated role. That replacement would then be absent from its historical assignment. Earlier completion of Renown, Repulse, or additional R- and Queen Elizabeth-class ships could change the calculation by enlarging the total pool.