ON those mornings that I go for a run along the Clyde walkway, I almost always pass La Pasionaria. For those unfamiliar with the great lady, La Pasionaria – or “passionflower” – was the name given to Dolores Ibarruri, a communist politician of Basque origin and Spanish Republican heroine of the fight against fascism during the civil war in the country in the 1930’s. “No Pasaran!” – they shall not pass! – was Ibarruri’s famous rallying cry during the battle for Madrid.

Today a stylised figure of her sits atop the Clyde walkway monument, erected in memory of those Glaswegians who volunteered for the International Brigade that fought against General Franco’s fascist forces in Spain.

Since boyhood the Spanish Civil War has been a near obsession for me. More than anything it’s the story of those ordinary people who upped and left behind their safe lives at home to journey and fight on the frontlines that has intrigued me most. That the International Brigades were made up from volunteers from across the world only adds to the fascination.

Scotland, with its strong socialist credentials of the time, provided its own share, as the dozen or so memorials across our nation attest to. In Glasgow I’m always saddened by how few people even know of the existence of the monument let alone the incredible history and sacrifice it represents.

The romance and idealism of an individual putting their life on the line for a cause they passionately believe to be just and right while combating the forces of evil has an allure as old as history itself.

In more recent times commentators have often looked for parallels with those who volunteered to fight for the Republic in Spain. I well recall meeting foreign volunteers battling Serb forces during the war in the former Yugoslavia in the 1990s. Some writers suggested they were the latter day equivalent of their 1930s counterparts, but I was never convinced of this. Most I encountered seemed more akin to mercenaries than idealists. It was a war, too, where differentiating between good guys and bad became increasingly blurred and ultimately impossible to determine.

What, then, should we make of those volunteers, British and others, who right now have joined the ranks of Kurdish fighters combatting the scourge of the Islamic State (IS) group in Syria?

Only this week Luke Rutter, a 22-year-old man from Birkenhead, and two young Americans became the latest volunteers to die in Syria after they were caught in an ambush in the IS stronghold of Raqqa. The Americans were Robert Grodt, an Occupy Wall Street activist and Nicholas Warden, who went to fight after being angered by IS-inspired terror attacks in Orlando, San Bernadino, Nice and Paris.

Young women volunteers have also joined the ranks of the Kurdish People’s Protection Units, or YPG, that has been a leading force in the ground battle against IS.

Kimberley Taylor, a 27-year-old from Blackburn, interviewed recently on the BBC said she sees the YPG female fighters as a beacon of hope for women in the region and around the world.

Almost all these young men and women, like their counterparts in Spain in the 1930s, identify with the progressive society the YPG is trying to create. In the Rojava region of southern Syria, the left-leaning YPG is attempting to implement a “social revolution,” building secular, multi-ethnic communities that prize gender equality, ecology, and direct democracy.

In many ways the YPG’s aim is not unlike that of some on the Spanish left of the 1930s who, as described in George Orwell’s famous book Homage to Catalonia, also sought to establish a socialist society out of the country’s civil war. For some of today’s international volunteers in Syria, IS represents the worst aspects of the state, conservative order and violent fascism. Josh Walker, 26, from Wales is one of them. “The militarism, the hierarchy, the repression, the prejudice, the misogyny, all of it rolled up into one in its most imperialist, genocidal form,” was how Mr Walker described IS recently in an interview with the online magazine The Intercept.

Mr Walker’s case also highlights the difficulty the authorities in Britain and other countries have in coming to terms with their nationals who have chosen to go and fight for the YPG. Now back in the UK, he has been charged under British counter-terrorism laws, the first anti-IS fighter to be prosecuted by British authorities on their return.

If reports are accurate however, it appears the charges relate to his possession of a partial copy of the infamous Anarchist Cookbook, a DIY explosives guide published in 1971 that has sold more than two million copies worldwide. In light of this, perhaps many of us would be advised to take another look at what lies on our home bookshelves. I certainly dread to think what the authorities would make of my own collection. But levity aside, the case of Mr Walker is a serious one and should he be found guilty of aiding and abetting terrorism after trial in October, he could face a 10-year jail sentence.

It’s estimated at least 300 Westerners have travelled to the Middle East to fight against IS, most of them with the YPG. The treatment they receive on their return home, however, varies. Travel bans, passport confiscation, charges made on suspicion of murder because of being a combatant, the returnees’ stories vary.

No one should be under any illusions about the mixed motives among those international volunteers who have gone to fight IS. Some have not gone out of idealism or support for a socialist vision of society. Even in Spain many who volunteered did so because they were adventurers, misfits or in trouble at home. In Syria too, some are ex-military who simply regard soldiering as what they do best, albeit against an enemy they universally despise. Earlier this year while in Iraq, I came across some ex-French commandos who fitted this description perfectly.

So should we salute these international volunteers who have gone to confront IS? Should we view their cause as largely just and worthy? I for one believe we should. I’d like to think La Pasionaria would also have approved.