The sister ships spent their whole careers assigned to the Home and Grand Fleets, often serving as flagships.

Aside from participating in the Battle of Jutland in May 1916, and the inconclusive action of 19 August several months later, their service during the First World War generally consisted of routine patrols and training in the North Sea.

The Colossus class were deemed obsolete by the end of the war in 1918 and were reduced to reserve the following year.

On 19 November 1908, Rear-Admiral Sir John Jellicoe, the Third Sea Lord and Controller of the Navy, proposed the changes that he would like to make to the Neptune's design.

Likely prompted by an earlier memo from Admiral Francis Bridgeman, commander-in-chief of the Home Fleet, Jellicoe wanted to eliminate the mainmast and transfer most of the functions of its spotting top to an armoured spotting tower atop the conning tower in the superstructure.

The Director of Naval Ordnance (DNO), Rear-Admiral Reginald Bacon, argued that the spotting top in the foremast should be retained.

Jellicoe was willing to slightly increase the new design's displacement over Neptune, but it could not cost any more, which placed major constraints on the Director of Naval Construction (DNC), Sir Philip Watts.

[1] The DNC objected to the loss of the mainmast as he believed that it was needed to support a boat-handling derrick, but was overruled by the Admiralty, which preferred to position the tripod foremast behind the forward funnel with the tripod legs facing forward to allow the vertical leg to be used to support the derrick.

The short height of the funnel also bedevilled the bridge with smoke until it was raised in 1912, although this exacerbated the problem for the spotting top.

The design also perpetuated siting the ship's boats on girders over the two wing turrets to reduce the length of the vessel.

The turbines used steam provided by eighteen water-tube boilers at a working pressure of 235–240 psi (1,620–1,655 kPa; 17–17 kgf/cm2).

They were rated at 25,000 shaft horsepower (19,000 kW) and were intended to give the dreadnoughts a maximum speed of 21 knots (39 km/h; 24 mph).

This gave them a range of 6,680 nautical miles (12,370 km; 7,690 mi) at a cruising speed of 10 knots (19 km/h; 12 mph).

Their secondary armament consisted of sixteen 50-calibre BL four-inch (102 mm) Mark VII guns.

[11] The Colossus class had a waterline belt of Krupp cemented armour that was 11 inches (279 mm) thick between the fore and rear barbettes that reduced to 2.5 inches (64 mm) outside the central armoured citadel, but did not reach the bow or stern.

The forward oblique 4-inch (102 mm) bulkheads connected the waterline and upper armour belts to the 'A' barbette.

In the interests of saving weight, the Colossus-class ships eliminated the anti-torpedo bulkheads that protected the engine and boiler rooms, reverting to the scheme in the older dreadnoughts that placed them only outboard of the magazines with the same thickness from 1 to 3 inches (25 to 76 mm).

[16] Fire-control technology advanced quickly during the years between the Colossus-class ships' commissioning and the start of World War I, and the most important development was the director firing system.

[18] Another development was the Dreyer Fire-control Table that combined the functions of the Dumaresq and the range clock in the transmission stations.

Hercules was probably fitted with a prototype table when its inventor, Commander Frederic Dreyer, was assigned to the ship at the end of 1911.

In addition, some machinery was removed during the refit to demilitarise the ship in accordance with the Washington Naval Treaty.

This grand battle was slow to happen, however, because of the Germans' reluctance to commit their battleships against the superior British force.

[24] In an attempt to lure out and destroy a portion of the Grand Fleet, the German High Seas Fleet departed the Jade Bight early on the morning of 31 May 1916 in support of Rear Admiral Franz von Hipper's battlecruisers which were to act as bait.

[26] Once Jellicoe's ships had rendezvoused with the 2nd BS, coming from Cromarty, Scotland, on the morning of 31 May, he organised the main body of the Grand Fleet in parallel columns of divisions of four dreadnoughts each.