Volunteering for war is a serious decision, not least when the country issuing the call to arms isn’t your own. Such decisions are all the more grave if those back home deem you to be fighting for the enemy.

Nevertheless, an estimated 45 Danes from a variety of backgrounds have made the fateful decision to join the fray in Syria. Commenting on the trend, Jakob Scharf, the chief of secret police service PET, said the development “was like nothing we have ever seen before”.

In fact, Scharf is wrong. The situation looks unmistakably like the situation Denmark saw between 1936 and 1939, when 500 Danes – organised primarily by the Communist Party – took part in the Spanish Civil War on the side of the Republicans against Franco’s pro-fascist forces.

If history is a lesson, Syria’s volunteers can expect rough treatment when they get home. The Spanish volunteers, after first being criminalised for their actions, later found themselves in history’s good graces, given that they, like the Danish Resistance, had combatted fascism.

Thanks to that turn of fate, the Spanish volunteers now have their own monument, prominently placed outside what is now the Museum of the Danish Resistance, in a park named after Winston Churchill. A more symbolic location would be harder to come by.

Fighting in another country’s war is serious business, particularly if you are hoping to return home able to practise the tools of the trade. Those who have gone off to war should have an eye kept on them when they return home, but according to journalists and others on the ground in Syria, most of the foreign volunteers are motivated less by ideology than a sense of adventure – precisely the same description that was made of the Spanish volunteers.

PET’s report and the ensuing media coverage were met with the predictable responses, not least from the right-wing, which fears that such volunteers would return to Denmark as terrorists. The message is clear: in political and security circles, fighting for Syrian liberation is the equivalent of proclaiming yourself a radical Islamist.

There’s no doubt these men will be influenced by their experiences in battle. Some may even come back as the Muslim agitators everyone is afraid of, and they should be dealt with accordingly – as were the two young men recently found guilty of receiving terrorist training in Somalia.

For most of these men, though, Syria is less a training camp than it is a cause. With the exception of a uniform and formal military training, what they are doing differs little from the actions of the Danish military in Iraq, Afghanistan and Libya. However, whether they too earn a monument for what they are doing is up to history to decide.