HMS Colossus was born out of an expedited measure on the part of the British Navy to expand its power, particularly as there were rumors of Germany conducting secret construction of its own new fleet of "Dreadnought" warships. With HMS Dreadnought having redrawn the design of the battleship when commissioned in 1906, HMS Colossus followed with a similar "all-big-gun" armament approach and steam turbine propulsion machinery to form a two-strong group of warships that included sister HMS Hercules. Approved in 1909, HMS Colossus saw her keel laid down by Scotts Greenock on July 8th of that year and she was launched to sea on April 9th, 1910 before being formally commissioned on August 8th, 1911. When introduced, HMS Colossus and her sister marked some of the last British steel warships to carry the 12" gun model as a primary battery - there proved a shift to the more potent 13.5" gun model with newer designs thereafter.
HMS Colossus and her sister benefitted in design over existing Dreadnought-type warships in that they were given greater armor protection. Armor protection reached 11" at the belt and turrets and 3" at the deck. To compensate for the expected weight gain, the aft-mast was excluded. The foremast remained but was integrated into the forward funnel which eventually presented some issues with the fire control system in play. Two smoke funnels dotted her silhouette in profile and her displacement reached 22,700 tons under full load. Dimensions included a length of 546 feet, a beam of 85 feet and a draught of 26 feet. Power was served through 18 x boilers feeding 4 x steam turbines driving 25,000 horsepower to 4 x shafts. Maximum speed in ideal conditions reached 21 knots. The crew numbered 755 in peace time a service though this total climbed to approximately 800 under war conditions.
At the heart of this warship was its armament fit led by 10 x 12" (304.8mm) BL Mk XII main guns held in five turrets fielding two guns apiece. One turret was set in the "A" position overlooking the forecastle with two centered around midships. The final two turrets lay towards the stern and gave the Colossus a fearsome broadside. Secondary armament was 16 x 4" (101.6mm) BL Mk VII guns. Colossus also carried 3 x 21" torpedo tubes which was a common practice concerning warships of the day.
HMS Colossus' first assignments were as part of the 2nd Battle Squadron (Home Fleet). She arrived in service just in time to take part in the first grand conflict of the 20th Century - World War 1 began in the summer of 1914 and would cover some four long years of fighting. In August of that year, HMS Colossus was made flagship of the 1st Battle Squadron.
The Battle of Jutland of May-June 1916 was the greatest naval battle of the First World War and involved participants Britain, Australia and Canada against Imperial Germany. The forces included 28 battleships to 16 battleships (respectively) as well as a slew of other lesser ship types. Germany sought to entice the Grand Fleet to combat in an attempt to break the British blockade enacted against the country - the blockade serving to severely hamper its merchant force. In the end, both sides claimed the victory and history marked the engagement as "tactically inconclusive" - though a "strategic victory" for the Allies. During the Battle, HMS Colossus took two direct hits that resulted in minor damage to her forward section but survived to fight another day.
From June 1916 until September 1917, Colossus was recalled for a refit. She followed the Grand Fleet to Rosyth for April 1918. The war drew to a close with the Armistice of November 1918. The Grand Fleet was then disbanded and HMS Colossus was given charge as flagship of the Reserve Fleet. By June 1921, her war-making value was limited by the restrictions set about through the Washington Naval Treaty. Marked for scrapping she was salvaged as a cadet training ship but her luck ran out in 1923 when she was sold off and ultimately scrapped by the end of 1928.