On 23 June of 2016, the United Kingdom will vote on an historic referendum, one in which the UK will decide whether or not to remain in the European Union. While most observers and ardent debaters tend to broadly focus on the economic implications of the “Brexit” movement at-large, a commonly neglected facet of the historic decision’s possible ramifications will impact the UK’s defense policy. This article examines a century of British military and diplomatic history, which highlights a trend of diminishing international military capacity and operational capability. Britain’s exit from the EU may very well negatively impact its ability to operate as a global military player.

In a May 2016 speech, former Mayor of London, Boris Johnson, echoing the sentiments of UKIP leader Nigel Farage in his 2013 address to the party, commented on the rationale behind the “Out” campaign, stating:

And of course there will be some in this country who are rightly troubled by a sense of neighborly duty. There are remainers who may agree with much of the above; that the economic advantages for Britain are either overstated or non-existent. But they feel uneasy about pulling out of the EU in its hour of need, when our neighbors are in distress; and at this point they deploy the so-called “Peace in Europe” argument: that if Britain leaves the EU, there will be a return to slaughter on Flanders Fields. This grossly underestimates the way Europe has changed, and the NATO guarantee that has really underpinned peace in Europe. I saw the disaster when the EU was charged with sorting out former Yugoslavia, and I saw how NATO sorted it out.

What often doesn’t surface until the end of most Brexit articles is what becomes of the UK’s place in the world should it leave the EU.

Those opposed to leaving the EU forcefully argue that in doing so, the UK would effectively sacrifice its influence in Europe, ultimately retreating from the successful international power networks of the 21st century that it helped to establish. To the more security-conscious supporters of the UK remaining in the EU, a British exit could spell a strained and less fruitful relationship with its closest ally, the United States.

In a recent speech, Prime Minister David Cameron, enumerated his argument on why the UK must remain in the EU. In his forceful address Prime Minister Cameron stated:

First, what happens in Europe affects us, whether we like it or not, so we must be strong in Europe if we want to be strong at home and in the world. Second, the dangerous international situation facing Britain today, means that the closest possible cooperation with our European neighbors isn’t an optional extra – it is essential. We need to stand united. Now is a time for strength in numbers. Third, keeping our people safe from modern terrorist networks like Daesh and from serious crime that increasingly crosses borders, means that we simply have to develop much closer means of security cooperation between countries within Europe. Britain needs to be fully engaged with that. Fourth, far from Britain’s influence in the world being undermined by our membership of the E.U., it amplifies our power, like our membership of the U.N. or of NATO. It helps us achieve the things we want, whether it is fighting Ebola in Africa, tackling climate change, taking on the people smugglers. That’s not just our view as well; it’s the view of our friends and allies, too.

On defense and while a debate on the security of a possible post-EU United Kingdom doesn’t often result in a raucous discussion, the very notion of a militarily weakened Britain undoubtedly strikes at the very core of the British identity. As historian Paul Kennedy masterfully demonstrated in his book, The Rise and Fall of Great Powers, for virtually the whole of the 19th century, Britain stood as the world’s preeminent power. After driving a massive stake into the hearts of the French at the Battle of Trafalgar in 1805, the British Empire, for some 60 years, collected its overseas holdings at an average rate of some 100,000 square miles per year. By 1860, Britain was responsible for 53 percent of the world’s iron production and some 50 percent of the world’s coal production. Britain alone accounted for 20 percent of the world’s total commerce. At the Empire’s territorial zenith following the conclusion of World War I, the British Empire covered approximately one-quarter of the world’s landmass, and some 600 million people lived within its transcontinental borders.

To safeguard and expand the British Empire’s commercial dominance, its modest, yet masterful British Army, and the unparalleled Royal Navy, coerced and outright decimated imperial opposition. For centuries, the United Kingdom sat as one of the world’s premier military powers, and for the better part of another century it alone sat as the world’s only superpower. Thus, for centuries military prowess has been an unwavering facet of both British national identity and national policy, ingrained frameworks that the Brexit movement overtly threatens.

Following the conclusion of World War I, a horrendously exhausted Britain began the gradual process of dismantling an empire upon which the sun never set. Britain had emerged from the Great War battered and bruised. It had lost more men in 1918 alone than it did during the whole of World War II. It, like other nations, struggled under a global economic system that had been crippled by war, and further weakened by a growing trend of the reflexive introduction of protective tariffs. While the British Empire remained largely the same in theory, in practice many of its dominions had been granted virtual independence by 1931.

Within a decade, the United Kingdom again was thrust into a devastating conflict, one that sounded the death knell of not only the British Empire, but of Britain’s status as a premier global military power. While emerging victorious from World War II, Britain had sustained severe economic damage. According to Kennedy, it was militarily overstretched, had worn out its domestic machinery, and depleted its gold and dollar reserves. Moreover, it had become largely dependent upon the United States, which emerged from the conflict not only more prosperous, controlling a full third of the world’s production, but the inheritor of Britain’s former status as a superpower.

In his iconic “The Sinews of Peace” Address at Westminster College in March of 1946, Winston Churchill prophetically commented on the radically shifting international power structure, stating:

Now, while still pursuing the method of realizing our overall strategic concept, I come to the crux of what I have traveled here to say. Neither the sure prevention of war, nor the continuous rise of world organization will be gained without what I have called the fraternal association of the English-speaking peoples. This means a special relationship between the British Commonwealth and Empire and the United States…

It should carry with it the continuance of the present facilities for mutual security by the joint use of all Naval and Air Force bases in the possession of either country all over the world. This would perhaps double the mobility of the American Navy and Air Force. It would greatly expand that of the British Empire Forces and it might well lead, if and as the world calms down, to important financial savings.

By the dawn of the 1950s, the decline of traditional European power, and Britain’s role as an unmatched global powerbroker had become readily apparent. Being overstretched and economically weakened following the war, it was deemed that decolonization and the erosion of Britain’s dominance on the global stage was inevitable. The ascendency of the United States provided a near constant flow of diplomatic and economic pressure that reinforced hypotheses that the international pecking order had dramatically shifted. Perhaps no better example can be found than the 1956 Suez Crisis, in which a combined Anglo-French-Israeli force attempted to take control of the Suez Canal. The United States, fearing that any resultant instability in Egypt could facilitate a communist incursion into the oil-rich Middle East, subsequently applied financial pressure and forced the allied force out of Egypt.

Nearly three decades later in April of 1982, Argentina seized the British Falkland Islands. The United Kingdom was called upon to muster its old military might and expel the Argentine invaders from its South Atlantic holding. By May of that year, the British invaded, and by June 14th, Argentina had surrendered. Hailing the rapid victory, Margaret Thatcher proclaimed:

This generation can match their fathers and grandfathers in ability, in courage, and in resolution. We have not changed. When the demands of war and the dangers to our own people call us to arms—then we British are as we have always been competent, courageous and resolute.

We have ceased to be a nation in retreat.

We have instead a new-found confidence—born in the economic battles at home and tested and found true 8,000 miles away.

That confidence comes from the re-discovery of ourselves, and grows with the recovery of our self-respect.

And so today, we can rejoice at our success in the Falklands and take pride in the achievement of the men and women of our Task Force.

But we do so, not as at some last flickering of a flame which must soon be dead. No—we rejoice that Britain has re-kindled that spirit which has fired her for generations past and which today has begun to burn as brightly as before.

Britain found herself again in the South Atlantic and will not look back from the victory she has won.

While Prime Minister Thatcher’s speech was eloquent and overflowing with national pride, her words belied that fact that in order to complete the recapture of the Falklands, the United Kingdom had to hire ships from private firms to augment its force. It ultimately concealed the reality that embarrassment during the Suez Crisis and even victory in the Falklands revealed, that there were definite and growing limits to British military power. Limits that would require the UK to continue to rely on international cooperation to secure its own global military reach, a process it engaged in through decades of progressive European integration, a process that ultimately culminated in the creation of the EU.

To that end, as new global powers emerged during the second half of the 20th century, Europe continued to integrate, eventually creating a political, economic, and military framework that in a sense has returned a collective Europe to the forefront of global power. While these modern military and diplomatic frameworks are far from perfect, it has allowed for the United Kingdom to not only spread a portion of the burden of international military operations to its near 30 fellow EU member states, but has allowed the UK to remain as one of the EU’s so-called “Big Three” states that largely dominate the direction of EU military operations and foreign policy.

The United Kingdom’s leadership within the EU’s military framework has not only allowed it to maintain its international military clout, but has also allowed it to truly defray the costs of less demanding military operations amongst its fellow EU member states, as was the case with the stabilization of the Balkans. While militarily the EU plays second to the UK’s favored defensive apparatus of NATO, in an era of military conflict dominated by the specter of international terrorism, the EU provides a beneficial emergency provision within the Lisbon Treaty, that provision being Article 222, which requires the mobilization of collective EU military resources in defense of the besieged member state.

Recently the Foreign Affairs Committee of the House of Commons released its Fifth Report on Session 2015-2016. In the report, the committee argued that the United Kingdom is the single most powerful state within the EU’s military and foreign policy apparatus, and that in essence it largely guides the whole of the EU. Effectively, the committee advanced the case that Britain’s leadership and status as Europe’s supreme military power allows it to steer EU military operations, making Britain a veritable force multiplier on the global stage.

In February of 2016, 13 former senior British military officers strenuously argued for remaining in the EU, stating that in the face of threats from terrorist groups and even conventional military threats such as an aggressive Russia, continued membership in the EU was “increasingly important.” In a May 2016 opinion piece written for The Telegraph, retired British Army Colonel Angus Loudon, MBE, stated that “Being part of Europe expands the capacity of our Armed Forces by bringing in troops alongside them. It also allows for specialisation.” Colonel Loudon continued by stating “Clearly, NATO is the cornerstone of Britain’s security. But the EU can do things and go places that NATO cannot…”

The defensive impact that undoubtedly worries Britons the most is what will become of the UK’s position in NATO, one of its chief international security bulwarks, should it abandon its position of military leadership within the EU. For many reasons, NATO has been the pillar of British security since the close of World War II, and a massive vehicle for the exertion of the British will abroad. In an era of not only marked by an unprecedented threat posed by extremism, the United Kingdom is also constantly looking to check the aggressive behavior of a hostile Russia, a trend that has carried over from the Cold War. To that end, in 2014 during the Wales Summit, Britain’s powerful position within NATO allowed it to spearhead the establishment of the Very High Readiness Task Force, which conducted operations in the Baltic States in order to keep them free of Russian incursion. Furthermore, Britain’s prominent role within NATO allows the nation to ensure her continued territorial sovereignty through the allocation and establishment of NATO assets, ranging from allied airbases to advanced missile defense systems, within Britain.

When it comes to NATO, all of the Brexit movement’s leaders, on both sides of the aisle, have voiced clear support for the US-led military alliance. There is an unusual cohesiveness between British statesmen on their affinity for NATO and the general belief that the alliance is of massive importance to UK defense and power projection. Yet like many issues concerning Brexit, opponents and proponents differ in their opinions on what will become of the UK’s role in the alliance should it withdraw from the EU. While “Out” campaigners such as Boris Johnson have argued that NATO has been the lynchpin for European peace in the post-World War II world, fellow “Out” supporter and Chief Executive of “Vote Leave” Michael Elliott argued that “The EU undermines our membership of NATO,” and that “It’s safer to take back control.”

However, many “Remain” supporters, as well as American military officials, believe that a British exit from the EU would have a negative impact on the strength of NATO. American Lieutenant General Frederick Hodges stated in March that “Anything that undermines the effectiveness of the alliance has an impact on us, and so if the EU begins to become unraveled, there can’t help but be a knock-on effect for the alliance also.” There appears to be significant credibility to General Hodges’ argument. As previously mentioned, the United States, the driving force behind NATO, has issued a rather stern request to member states that they increase they maintain defense budgets that total at least two percent of their GDP. Such a call signals a growing American concern that the United States is becoming unwilling, or projects that it will at some point be unable, to serve as the bulwark for European defense. In light of a British withdrawal from the EU, which has allowed the UK to disperse a portion of its defense costs and burdens amongst its fellow member states, one wonders in the face of the ever-present threat of austerity cuts to essential domestic programs, if it would be able to maintain an adequate level of defense spending without membership in the EU.

When it comes to the British military legacy and the impacts of Brexit upon UK defense, there is a significant logistical or numerical impediment to supporting the Brexit and the resultant expectation that a militarily more capable Britain will emerge. As it stands, the British Armed Forces possesses only 144,000 personnel in total, leading some publications to chastise the government for allowing the total number of soldiers to fall below the total number of hairdressers within the United Kingdom. The Royal Navy, the necessary vehicle for power projection and expeditionary operations, is without an aircraft carrier until 2020 and currently only possesses 19 surface warships, meaning it has twice as many admirals as it does frigates or destroyers. Worse yet, military recruitment has plummeted by some 30,000 individuals over the last three years.

What cannot be avoided are the realities of the UK’s military limitations. Nor can one turn a blind eye to a century of British military and diplomatic history in which the UK’s military power has steadily risen along with its dependence on foreign allies. The unsavory truth is that a nation of 60 million inhabitants whose status as a leading global economy is under the inevitable threat of usurpation by developing nations, simply cannot sustain the level of defense spending that would be required to ensure that the UK remains a global military power, a tall order given UK defense spending as a percentage of GDP has been halved since 1982. Short of drastically increasing its defense budget to cope with the loss of the EU’s “force-multiplier” effect, its withdrawal from the EU would most likely throw the EU into disarray, strain its relationship with the United States, and damage its international clout, all of which would degrade its military might.