The Spanish conflict cut across both states and population groups and gained significant symbolic importance already during the events themselves. This was certainly the case in Belgium. Overall, the left-wing parties and trade unions supported the Republic, while the right-wing, Catholics and radical-right nationalists, sided with Franco. The liberals remained the least outspoken and were partly divided on the issue. Both camps developed a strong emotional involvement towards the civil war. On the left, this was characterized by widespread solidarity actions. A notable aspect of this was the care for hundreds of mainly Basque war children. However, the most iconic aspect remained the estimated 1,600 Belgians and at least 800 foreigners residing in the country who went to Spain to defend the Republic by force of arms or to serve in the sanitary services.

The Belgian government declared itself 'neutral' and, at the same time, wished to maintain the foundations of bourgeois democracy. In harmony with the 'neutrality policy' that characterized Belgium's foreign policy in 1936, the government joined the Non-Intervention Committee (NIC) that had been established in London. From the outbreak of the civil war, Germany and Italy had provided significant, if not decisive, aid to the rebellious military forces around General Franco. France and Great Britain then took the initiative to create the NIC. The Soviet Union, Germany, and Italy also officially joined. It didn't take long before the Soviet Union decided to actively support the legally elected Republican government.

The stance the Belgian government took regarding the volunteers in the Spanish conflict was partly a result of domestic power dynamics and partly a result of decisions made in the international forum of the Non-Intervention Committee. Initially, the NIC committed to banning the supply of weapons, and only later were volunteers discussed. On December 22, 1936, Belgium accepted a British proposal to put an end to the influx of foreign volunteers into Spain. On January 1, 1937 a law made it punishable for individuals to recruit people by means of "gifts, payments, promises, threats, abuse of authority or power (...) on behalf of a foreign army or foreign troops". Appealing to idealism remained not punishable and the law only concerned the recruiters.

The attitude of the Belgian government towards the volunteers changed in February 1937 when the NIC member states committed to extending the non-intervention agreement to all non-Spaniards who wished to engage in the civil war. In June, an emergency law came into effect that made all recruitment, as well as any departure or transit to Spain, punishable. However, the vast majority (estimated at a minimum of 80%) of the Belgian volunteers for the Brigades had already left. Meanwhile, indirect means had been used to target the volunteers. There were three such measures: failure to report a change of residence, neglect of family, and desertion. The only significant prosecutions were those instituted for desertion. Before the Military Councils, 310 cases were brought leading to 163 convictions, resulting in a few days of military arrest. It is clear that these prosecutions, despite the growing fear of the 'red danger,' took place within the democratic framework of the liberal Belgian state. Thus, this political repression was negligible compared to what many of these former Spanish fighters faced during the occupation.