In 1914 the Royal Navy was by far the most powerful navy in the world. The Royal Navy's basic responsibilities included policing colonies and trade routes, defending coastlines and imposing blockades on hostile powers. The British government took the view that to do all this, the Royal Navy had to possess a battlefleet that was larger than the world's two next largest navies put together.

By early 1914 the Royal Navy had 18 modern dreadnoughts (6 more under construction), 10 battlecruisers, 20 town cruisers, 15 scout cruisers, 200 destroyers, 29 battleships (pre-dreadnought design) and 150 cruisers built before 1907.

After the outbreak of the First World War, most of the Royal Navy's large ships were stationed at Scapa Flow in the Orkneys or Rosyth in Scotland in readiness to stop any large-scale breakout attempt by the Germans. Britain's cruisers, destroyers, submarines and light forces were clustered around the British coast.

The Mediterranean fleet, of two battlecruisers and eight cruisers were based in Gibraltar, Malta and Alexandria. These were used during the operations to protect Suez and the landings at Gallipoli. There were also naval forces in Canada, Australia and New Zealand.

In August 1914 Admiral Sir David Beatty devised a plan to draw the German Navy into a major sea battle. Beatty used two light cruisers, the Fearless and Arethusa and 25 destroyers to raid German ships close to the German naval base at Heligoland. When the German Navy responded to the attack, Beatty brought forward the battleships, New Zealand and Invincible and three battlecruisers. In the battle that followed, the Germans lost three German cruisers and a destroyer. The British ship, the Arethusa was badly damaged but was towed home to safety.

The British Navy suffered three early shocks. On 22nd September, 1914, German U-boats destroyed the Cressy, Aboukir and Hogue with the loss of 1,400 sailors. This was followed by Audacious, a dreadnought completed in late 1913, sinking after hitting a mine off the northern coast of Ireland. After this, the Royal Navy became very cautious and restricted itself to unadventurous sweeps of the North Sea.

In December 1914 Admiral Franz von Hipper and the First High Seas Fleet bombarded the costal towns of Scarborough, Hartlepool and Whitby. The attack killed 18 civilians and created a great deal of anger against Germany and the Royal Navy for failing to protect the British coast.

Admiral Hipper planned to make another raid on 23rd January, 1915, but this time his fleet was intercepted by Admiral David Beatty and six fast cruisers and a flotilla of destroyers. The British shells damaged the ships, Sydlitz and Bloucher but the German's retaliated and damaged Beatty's flag ship, the Lion. Afterwards, both sides afterwards claimed Dogger Bank as a victory.

The only major wartime confrontation between the Royal Navy and the German High Seas Fleet took place at Jutland on 31st May 1916. The British lost three battlecruisers, three cruisers, eight destroyers and suffered 6,100 casualties; the Germans lost one battleship, one battlecruiser. four cruisers and five destroyers, with 2,550 casualties. The Royal Navy was shocked by the outcome considering that it clearly outnumbered outnumbered German forces (151 to 99). However, Jutland was seen as a victory by the British commanders because it reinforced the idea that the Britain had command over the North Sea.

After Jutland the Royal Navy's main preoccupation was the battle against the German U-Boats. The war against submarines in the Mediterranean and home waters was vital to the British war effort and it was not until the autumn of 1917 that the transportation of troops and supplies from the British Empire to Europe could be made with confidence.

During the First World War the Royal Navy lost 2 dreadnoughts, 3 battlecruisers, 11 battleships, 25 cruisers, 54 submarines, 64 destroyers and 10 torpedo boats. Total naval casualties were 34,642 dead and 4,510 wounded.