Sometime in 1912, the compass platform was extended forward to accommodate a rangefinder. In 1913–1914, a small rangefinder was added to the roof of 'X' turret and gun shields were fitted to the 4-inch guns in the forward superstructure. After the start of the war in August 1914, a pair of 3-inch anti-aircraft (AA) guns were added. A fire-control director was installed on a rear extension of the compass platform by December 1915. Approximately of additional deck armour was added after the Battle of Jutland in May 1916. Around the same time, four 4-inch guns were removed from the aft superstructure. By April 1917, "Hercules" was equipped with single 4-inch and 3-inch AA guns and the forward group of 4-inch guns had been enclosed in casemates. The stern torpedo tube was removed in 1917–1918 and a high-angle rangefinder was fitted on the spotting top in 1918.