What the modern navy did for us

But this view is wrong. Winston Churchill famously said that Admiral Sir John Jellicoe, commander of the Royal Navy’s Grand Fleet, was “the only man... who could lose the war in an afternoon” – because defeat could lay the country open to starvation and a German invasion.

Not only did the navy prevent an invasion, it also chalked up three other major achievements. First and most important was its defeat of the German submarine fleet, which might have starved Britain into submission. Second, millions of troops and their supplies were transported safely to and from European battlefields. Its third triumph was a little-heralded war-winner: the blockade of Germany.

Germany collapsed in 1918 because the Royal Navy cut off its sea transport, devastating industrial and agricultural output, producing shortages both on the front and at home, and hammering morale. By 1918 the Germans had insufficient copper for secure communications, and meat rations were just over 10 per cent of the prewar average. As a result, in late 1918 sections of the German High Seas fleet mutinied and refused to go to sea.

Victory was built on the relentless application of naval power. Without it, Britain couldn’t have won.

The Royal Navy... prevented the invasion of Britain in the Second World War

The summer of 1940 was a torrid time for Britain. An unsuccessful campaign in Norway was followed by the fall of France to Germany, Italy’s entry into the war on the side of the Axis, and the Battle of Britain.

But one thing Britain never seriously had to face in the following war years was the prospect of an invasion. That was not because of the efforts of the RAF’s pilots in the Battle of Britain, heroic though they were in defeating the Luftwaffe. It was thanks to the Royal Navy.

Though badly managed, the Norwegian campaign had chalked up one significant achievement: the destruction of large numbers of German surface ships. Ten destroyers were sunk or scuttled at Narvik; a couple of cruisers and dozens of supply and support ships were sent to the bottom elsewhere in Norway; and a number of other major warships were badly damaged. The German Kriegsmarine (surface fleet) was seriously weakened.

True, some Royal Navy ships were lost – notably the aircraft carrier Glorious, together with the destroyers Acasta and Ardent (the latter being the forbear of the ship that I captained during the Falklands War). But the navy still had a huge surface fleet – one that it used to pack the English Channel and North Sea with ships, making an invasion a practical impossibility.

The Royal Navy... ensured Estonian independence

As the First World War drew to a close, tens of thousands of British troops went into action in a conflict that is rarely discussed in Britain – the Russian Civil War. The history of the Royal Navy’s involvement is extraordinary. Sent to defend Britain’s interests and to fight a new ideology perceived as dangerous, it ended up acting as midwife to a new European nation-state: Estonia.

The Royal Navy saw action across Russia. In the Caucasus, it deployed the largest fleet ever to sail on the Caspian Sea, sent there to defend Britain’s vital oil interests. In the north, the fleet engaged in vigorous fighting at Arkhangelsk and Murmansk – a hole was blown in the side of the coastal monitor M33, which can still be seen at Portsmouth Historic Dockyard. And at the Russian naval base at Kronstadt, seat of the Russian Revolution, naval officers and ratings won a number of Victoria Crosses for their heroism.

But the most surprising outcome of the conflict was the emergence and independence of Estonia. The Royal Navy delivered weapons, captured and handed over to the Estonians two Soviet destroyers, and provided support up the coast and protection against Soviet forces.

Estonia lost its independence during World War Two, regaining it only after the collapse of the Soviet Union. But the Royal Navy’s efforts in 1919–20 are still recognised gratefully in Estonia. I vividly remember being guest of honour at the unveiling of a memorial in Tallinn dedicated to Royal Naval sailors killed defending Estonia’s independence; a year later I attended the unveiling of a similar memorial in Portsmouth Cathedral, also funded and erected by a grateful Estonian nation.

The Royal Navy... beat Rommel in north Africa

The Second World War in the Mediterranean was grisly. The Royal Navy made early progress against the Italian navy and pushed into Crete. But during the vicious German counter-attack the navy suffered terrible losses while evacuating the army. Still, the navy survived and, with the support of the population of Malta, was able to keep that rocky island in the heart of the Mediterranean resupplied, and to prevent it from falling into Axis hands.

That defence was vital. From Malta, Royal Navy submarines and surface vessels, together with RAF planes resupplied by the navy, relentlessly attacked Axis supply lines to north Africa. With the benefit of decrypted intelligence detailing the ships that were leaving for Africa, those sorties were devastatingly effective.

Erwin Rommel, the great German general in charge of the Axis campaign in north Africa, once noted that “battles are decided by the quartermasters before the first shot is fired”. He knew from bitter personal experience. In late 1942, with General Bernard Montgomery’s 8th Army pressing for a victory, Rommel’s troops ran short of fuel and ammunition, leading to defeat at the battle of El Alamein. It was the first major Allied victory since the start of the European war in 1939, and one that safeguarded access to the oilfields of the Middle East.

By early 1943, the Germans were facing defeat in north Africa. Admiral Andrew Cunningham, the Royal Navy commander in the Mediterranean, signalled the fleet to “Sink, burn and destroy: Let nothing pass.” Just as they had when facing defeat in Crete two years earlier, his officers and men followed his orders to achieve a stunning victory.

The Royal Navy... created British intelligence services

Britain’s modern intelligence services trace their roots to the Royal Navy. Indeed, some of the most dramatic intelligence breakthroughs of the First World War were made in Room 40 of the Old Admiralty Building.

Set up to decrypt intercepted messages, the intelligence that came from Room 40 helped the navy to avoid numerous German traps at sea – and to spring some British ones. And the ‘Zimmermann Telegram’ of 1917 (in which Germany invited Mexico to join the Central Powers should the US side with the Allies), intercepted by Room 40, was critical in bringing America into the war alongside Britain.

In time, Room 40 spawned the code and cypher school at Bletchley Park – which proved so crucial to Allied military success during the Second World War – and, ultimately, the modern GCHQ. The Royal Navy shared these lessons with Britain’s allies, helping the US Navy learn how to intercept Japanese codes – without which they might not have won the battle of Midway in 1942, the most important naval battle of the Second World War in the Pacific.

But naval intelligence was about collecting human intelligence as well as intercepting enemy communications, and some naval traditions persist in intelligence to this day. The head of MI6 (called ‘C’, after Captain Sir George Mansfield Smith-Cumming, the officer who established the service) still writes with green ink – because that is what admirals use.

The Royal Navy... showed how to deter an Iraqi attack on Kuwait

The scenario is familiar: an Iraqi ruler aspiring to lead the Middle East, with his eye on massive oil reserves and productive oil fields in nearby Kuwait, and troops massing on the border. In 1990 the result was an invasion, the mobilisation of a huge international coalition against Iraq, and a swift but costly war with long-lasting consequences for the region.

In 1961, Iraqi ruler Abd al-Karim Qasim declared his designs on Kuwait – but this time there was no war, in large part because of the presence in the region, on board HMS Bulwark, of 42 Commando Royal Marines. They swiftly deployed into Kuwait, while the Royal Navy was also able to land tanks using the amphibious force based in Bahrain. Fixed-wing air support was provided by HMS Victorious.

The force was not large, and might have been overwhelmed by an Iraqi attack, but as a stopgap measure and deterrent it did the job. With Royal Marines in place inside Kuwait, Qasim knew that any attack would bring a wider and firmer British response.

Just five years earlier, HMS Bulwark had taken part in the attack on the Suez Canal, an episode that proved such a humiliating failure for Britain. Now Bulwark, the Royal Marines and the Royal Navy were part of a force which, in its defence of Kuwait, began to restore British prestige in the Middle East. In the process it protected a country that held a quarter of the world’s known oil reserves, that provided almost 40 per cent of Britain’s oil, and which invested around £100m each year in Britain.

The Royal Navy... defended democracy in Tanganyika (now Tanzania)

In January 1964, a mutiny broke out in the army of the newly independent east African state of Tanganyika (which later that year joined with Zanzibar to form Tanzania).

The troops of 45 Commando Royal Marines, based in Aden, were hurried onto the light aircraft carrier HMS Centaur. So when the Tanganyikan president Julius Nyerere requested British assistance, the Royal Marines were able to help at short notice. They landed by helicopter on the morning of 24 January just outside the then capital, Dar es Salaam. With a nearby frigate firing air-burst shells, and rocket launchers either side of the landing site, by seven o’clock in the morning they had suppressed opposition at the main Colito barracks. They proceeded to pacify troops elsewhere, and snuffed out the nascent rebellion.

Normality was gradually restored in the city and control was returned to the elected government – an example of how Britain could protect the interests of its former colonies.

The Royal Navy... helped end the Cold War

In the 1970s and 1980s, Soviet leaders such as Leonid Brezhnev and Yuri Andropov believed that they would win the Cold War. This belief was built on a set of Soviet assumptions about Britain and the west – assumptions that were exposed as badly mistaken by the events and outcome of the 1982 Falklands War.

Britain’s victory in the Falklands, built on the power of the Royal Navy, was a shock to the Soviet system at a number of levels – from general psychological points to very specific military tactics.

First, the Soviets believed that the west was... well, a bit soft, and not ready to fight a war. Second, after years of decline and economic difficulty, it was easy to look at Britain in the early 1980s and wonder how on earth it could pull together a task force sufficiently powerful to recapture the Falkland Islands. Third, Soviet military doctrine relied heavily on using missiles to break up a task force or carrier group.

But the Royal Navy was well trained and ready for a fight. The navy’s ability to pull together a carrier task group and sustain it thousands of miles away was eye-opening. And though my ship, HMS Ardent, and four others were sunk, by the end of the war we had worked out how to deal effectively with even advanced Exocet missiles. The outcome of the war, and the performance of the Royal Navy, upended Soviet assumptions about how well placed they were to win the Cold War, and made them realise that to do so would involve a long and costly slog.

Admiral Lord West served in the Royal Navy for 40 years, rising to become First Sea Lord (professional head of the navy) from 2002 to 2006. Between 2007 and 2010 he was minister for security and counter-terrorism.

This article was first published in the June 2014 issue of BBC History Magazine