A complicated war rages halfway round the world. Young men, keen for adventure and often without military experience, are browsing media when they find someone attempting to recruit fighters for the war. They sign up and their participation in someone else’s war has serious repercussions.

They themselves are placed in great danger. Some are executed. At home, a heated parliamentary debate begins on the dangers of young men becoming foreign fighters, and what to do about it.

So far, so familiar. Except the war was in Angola in the early 1970s and the young men were mercenaries recruited through newspaper ads to fight for the National Liberation Front of Angola. In 1976, 13 British and American mercenaries were captured and put on trial for the crime of “mercenarism”. Two were executed.

The controversy played out in the newspapers and in parliament. Eventually, the UK government called upon Lord Diplock to consider the legislative means that existed or could be created to control mercenaries.

The case of the Angolan mercenaries has disappeared from the public memory, despite its obvious parallels to the current problem of foreign enlistment in the form of young people going to Syria to join Islamic State (IS). Even better-known episodes of foreign volunteering in combat seem to have been forgotten. An estimated 30,000 people joined the International Brigades during the Spanish Civil War.

Some 1500 Canadians even formed their own battalion. After the International Brigades disbanded, the Canadians struggled to return home. These men were not allowed to serve in the second world war because of suspicions about their politics. Returning American brigade fighters faced similar problems.

The parallels between these past cases of foreigners fighting abroad and today’s problems are many and interesting. There is a long history of young people drawn to conflicts abroad, for passion or for money or for adventure. We have forgotten that foreign fighters are a normal part of war.

Before the 18th century, all European armies employed foreigners in large numbers in various capacities. Some officers were particularly sought after because they had extensive experience fighting in different wars for different employers.

It is equally important to remember that in many cases, such as the Spanish Civil War or soldiers enlisting in the British military before their own states joined the second world war, we occasionally even find the idea of fighting abroad admirable. Treating foreign fighters as a perversion of war denies historical reality.

Problems of departure and return

Two main problems have always been associated with foreign fighters: how to prevent them going, and what might happen when they return. History provides us with interesting ways of considering both problems.

The Diplock Report in 1976 was concerned with preventing the departure of mercenaries in the first place. However, after lengthy analysis, Diplock concluded that the various measures that could be brought to bear against putative mercenaries were useless. In particular, the removal of passports was a “minor obstacle to departure”.

Foreign enlistment acts have also been largely unenforceable. Even despite greatly enhanced surveillance measures and the ability to check passports electronically, the same problem rears its head today. Countries can stop people they know will be interested in joining IS; they can’t stop the ones they don’t know about. Restricting or scrutinising travel to particular destinations is no solution, as would-be foreign fighters can simply take a circuitous route.

Another issue with controlling exit is that it contradicts the right of free movement. In the 1970s, Diplock determined that the potential threats caused by mercenaries were not so grave that they justified overturning this basic right. Today, governments around the world are much more concerned about the potential security challenge posed by returning foreign fighters and have been vastly more vocal about the need to restrict free movement.

Security threats on two fronts

Foreign fighters can pose a security threat in two ways. They can, by participation in a conflict, alter its course in such a way that it damages the interests of their home state. This is precisely the concern behind the creation of foreign enlistment acts in a number of states in the late 19th century. They can also return home with skills or political views that pose a domestic security risk.

The history of foreign fighters shows that it is much easier to control return rather than departure, which mitigates against the problem of domestic security risk. The Spanish Civil War veterans who faced difficulties enlisting in the Canadian military faced them even without the electronic organisation of information and internationally connected passport controls of today.

Unless foreign fighters are smuggled back into the country, they can simply be stopped from re-entering, especially given the propensity for foreign fighters from states like Australia to declare themselves publicly in online videos.

What kind of domestic security risk do foreign fighters pose? In the past, foreign fighters may well have come back home with political ideas or military skills unavailable to them in peaceful Canada or Australia. But today the political information and the military skills are accessible without ever having to leave home.

The Melbourne boy charged with plotting a terrorist attack on Mother’s Day learned his craft from his own computer. Controlling the return of foreign fighters is unlikely to control the return of information that could pose a threat to the state.

Foreign fighters may well be complicating the war in Syria. They certainly add to the manpower available to IS.

Their presence is also a very useful propaganda tool, as it was for the International Brigades in the Spanish Civil War, because it demonstrates the attractiveness of IS ideology. Foreign fighters serve the additional function of drawing attention from around the world, as their home states focus on telegenic doctors or unexpected jihadis in the nightly news.

Given that history shows it is at best difficult and at worst impossible to prevent foreign fighters from joining a conflict, and given that foreign fighters are a normal part of war, what should states do? One answer may be that giving the problem such heightened attention simply gives it greater life. Endless debates in parliament, combined with draconian powers that will control only known foreign fighters, may simply be an even better recruitment tactic than placing an ad in the Sunday papers.

Finally, it is worth highlighting that in debates on foreign enlistment, going back as far as the Hague Conference of 1907, concerns about violating the fundamental right to freedom of movement have outweighed fears about the problems that foreign fighters might cause.

We must consider whether or not today’s security situation, especially given the easy access to dangerous information on the internet, is really so different as to warrant the reversal of this position.