Following the Russian invasion of Ukraine, President Zelensky created the International Legion for the Defence of Ukraine, hosting 17,000 voluntary soldiers from different countries. This decision brought the spotlight on the phenomenon of Foreign Fighters. Nevertheless, this is hardly something new. Since the 19th century, foreign volunteers have participated in civil conflicts such as independence wars in Greece and South America or the Spanish civil conflict. Recently, volunteers arrived in Syria and Iraq to join the Islamic State of Iraq and Syria (ISIS) drove the interest of academic researchers. By contrast, those who instead joined the Yekîneyên Parastina Gel (YPG) and the Yekîneyên Parastina Jin (YPJ) have received lesser attention. We still do not have precise estimates of them and know little about why they decided to fly to Syria. Contro lo Stato Islamico. I Foreign Fighters occidentali nella Guerra civile siriana bridges this gap, examining why young Westerners chose to join the Kurdish fight against ISIS. Moving from this question, the book opens the field to other issues, such as their impact on the war and how states managed their returns. Interestingly, it also challenges current academic literature on the relationship between foreign fighters and local populations.

The book is composed of four chapters, which drive the reader through the Syrian civil war and foreign fighters’ lives among YPG and YPJ. Initially, the volume reviews the academic debate on foreign fighters, clearly defining the phenomenon and picturing its historical development. Next, it illustrates the Syrian civil war, examining the origin and development of the conflict and the parties involved in it. Once the reader has a complete picture of the situation, the book focuses on the foreign fighters who decided to join YPG and YPJ. Their characteristics, motivations and the problems – legal and medical – they faced in returning to their home countries are studied through a series of interviews. In total, Corradi interviewed 19 persons, coming from Italy, the UK, the USA, Denmark and Ireland.

The empirical analysis reveals common patterns among the interviewees and profound differences between them and those who instead decided to join ISIS. Although the role of women in the YPG and YPJ was crucial, 90% of the sample is composed of men. If this trait is shared between those who fought in the Kurdish army and those who joined ISIS, the average level of education differentiates them. Most completed high school, nine have a bachelor's degree and two have a PhD. By contrast, ISIS foreign fighters had a lower level of schooling. The age also shows differences between the two groups. Among YPG and YPJ, 65.51% of foreign fighters were between 20 and 34 years old when they first arrived in Syria, thus older than those who fought for the Islamic State. Lastly, almost all the interviewees declared to be close to left-wing movements, either communist or anarchist, even if none were in a specific party. The book also examines the rationales behind this choice. Through an original division between “push” and “crucial” factors, the author shows how the former, especially ideology and emotions for what the Islamic State was doing, were the first elements to originate the idea to join YPG and YPJ. Yet, they were not enough; crucial factors were needed. Indeed, to convince the interviewees was a feeling of grievance for what was happening and the willingness to help the Kurdish: “In 2014, I discovered what was happening to the Yazida population, and I discovered that Kurds accepted volunteers. In that period, the relationship with my wife was not going well, and I was not earning too much. The Islamic State had already attacked twice in the USA, so I seized the moment. I went there” (p. 95).

However, the most interesting discussion is the study of their actual impact on the war and, above all, of the relationship between foreign fighters and the local population. Regarding the first aspect, the analysis highlights that the impact of foreign fighters on the war was relatively low; nevertheless, their participation was crucial in boosting the morale of the local populations, showing them that the world was supporting their fight. The relationship with the locals is precisely the most novel result of this book. Contrary to what previous literature has claimed, Corradi underlined how, in this case, the relationship was extremely good. This is another factor that differentiates those who joined YPG and YPJ and those who fought for ISIS: during the same period, the Islamic State killed 16,827 civilians, the other side 927. According to the author, these differences might be explained by three main elements: ideology, how YPG and YPJ governed the liberated cities and how they managed foreign fighters, often separated from the local population.

Lastly, the book analyses interviewees’ return to the homeland, underlining some common traits. For many of them, the return was maybe the most difficult challenge. Many had to face legal processes based on anti-terrorism laws and were posed under strict examination by the police, scared that they could use what they learned in the war in their countries, although, so far, none of that has happened. Others instead had to recover from post-traumatic stress disorder.

This volume connects a rigorous methodological approach with friendly writing that opens the minds and hearts of those who decided to join the fight against ISIS to the reader. Corradi masterfully reconstructed foreign fighters’ lives before, during and after the war. To some extent, the volume also appears to be a memoir of the fighters, reminding publications of Red Brigades’ biographies. Thus, besides being a well-rounded academic publication, the book is easily accessible to a non-expert public. It also has the merit to call attention to cases, YPG and YPJ, understudied by the academic literature, so far more interested in the Islamic State and its foreign fighters. Hence, the volume connects with the most up-to-date research on civil conflicts, bringing new cases and results to public attention. However, some limitations deserve mention. As the author recognises, the sample is relatively small, limiting the generalisation of the conclusions. Similarly, a deeper comparison between YPG, YPJ and ISIS's foreign fighters would have enriched the book. Despite these limitations, the book contributes significantly to the literature on foreign fighters and the motives behind the choice to join a war far away from home. Thus, the volume is an advisable reading for those interested in these topics, being them students, young scholars or a more general audience.