Increasingly, some of the volunteers have opted to concentrate on medical and charity work. Duncan has raised money for night-vision scopes, assault vests, webbing and other gear, especially quick-clotting Celox-A for treating wounds. Kevin Burns wrote in February that “I’m going to be putting my civilian fire and EMS skills to use for the Peshmerga 9th brigade by setting up a field hospital and teaching American triage.” Macer Gifford, a British volunteer who has returned to Syria twice, announced in August 2016 that “with the help of hundreds of supporters” he had brought 150 medical packs to the YPG’s Tactical Medical Unit to treat hundreds of injured SDF fighters and civilians.

There have been many controversies among the volunteers, especially among those who think others are profiting off their experience. Jesper Sorder, a Swede, was heavily criticized by his former comrades after he wrote a book, as was Joanna Palani, a Danish woman who claimed that “ISIS soldiers are easy to kill.” Tim Locks, a British volunteer, was criticized for his book by others who felt that he hadn’t seen much action. There are also many disputes about some of the charities set up by volunteers that seek to aid the Kurds, with some volunteers claiming that others who administer charities or Facebook pages are running fraudulent ventures that only exist on paper.

The war against ISIS in Iraq and Syria has brought together several hundred men and a few women—volunteers from all over the world. Hailing from Spain, Scandinavian countries, Egypt, Greece and Mexico, they are truly international. A disproportionate number are from English-speaking countries, particularly the UK and the United States. This could be due to the longstanding American and British involvement in Iraq, and feelings of responsibility for what happened to the country. There appears to be a larger consensus among the volunteers that fighting ISIS has commonalities to the shared experience that Americans and British had fighting the Nazis, and a sense of moral obligation to defend minorities. Many of these volunteers felt their countries should have done more in 2014 to stop ISIS’s advance.

As the conflict winds down with the advance toward Raqqa in Syria and Mosul in Iraq, many of these volunteers who are still there will find themselves members of a unique fraternity, brought together by especially terrible circumstances that emerged in August of 2014. In many ways, they are the diametric opposite of those who joined ISIS. Rarely before in history has a conflict like this inspired so many Westerners to leave behind their lives to volunteer on a foreign battlefield. Some will stay behind, or marry Kurds, as Matson did. But most will return home with a war experience they cannot communicate to those around them, and with little support networks for what they have been through.

Seth J. Frantzman is a Jerusalem-based journalist who holds a PhD from The Hebrew University of Jerusalem.

Image: A Peshmerga soldier takes lead during urban combat maneuvering training Octobert 29, 2015, near Erbil, Iraq. Flickr/U.S. Department of Defense