Fire-control technology advanced quickly during the years immediately preceding the First World War, and the most important development was the director firing system. This consisted of a fire-control director mounted high in the ship which electrically provided data to the turrets via pointers, which the turret crew were to follow. The director layer fired the guns simultaneously which aided in spotting the shell splashes and minimised the effects of the roll on the dispersion of the shells. A prototype was fitted in "Dreadnought" in 1909, but it was removed to avoid conflict with her duties as flagship of the Home Fleet. Preparations to install a production director were made during her May–June 1915 refit and every turret received a rangefinder at the same time. The exact date of the installation of the director is not known, other than it was not fitted before the end of 1915, and it was most likely mounted during her April–June 1916 refit.