This is a good question, and one that highlights the cultural impact of the Spanish Civil War - not just within Spain, but as a cultural touchstone across Europe (and the world).

There’s a couple of problems in actually answering though. The first is defining ‘side’. Do you mean specifically Spaniards who participated in either side of the struggle, or even just lived in the corresponding zone? Do we include Spaniards living outside of Spain (hello Salvador Dalí and Pablo Picasso!)? Do we include non-Spaniards who were active supporters of either side, inside or outside of Spain? The latter definition is a particularly important one here, as I’ll get into below.

The second issue is assessing relative cultural worth. I can tell you which art I prefer, but by definition cannot tell you what is objectively better. Each side created art and media for its own target audience, drawing on different themes, styles and references. If you like religious art, or monolithic fascist-y architecture, then Francoism delivers! If you like abstraction, or socialist realism, then let’s talk Republicans.

But if we want to talk about fame as the key metric of cultural output, then the Republic is a clear winner. From iconic novels (For Whom The Bell Tolls), to the latest thing in war photography (Robert Capa, Gerda Taro), film (Spanish Earth), painting (Picasso’s Guernika), singers (Paul Robeson) or poetry (e.g. Federico García Lorca), the Republican side either consisted of or attracted some of the top talent of the 1930s, who created iconic representations of the conflict across many media. Many of these representations have stood the test of time, and are still admired today.

It was no coincidence that in terms of international talent at least, the Republic attracted the lion’s share of support. Artists, writers and intellectuals were among the earliest to appreciate fascism for what it was – the impact of Nazism in particular on creative self-expression was not lost on an international cultural elite. Not only was German cultural output immediately curtailed by Nazi censorship, the impact of Nazi racial laws on artists and performers was considerable – any institution reliant on public funding was directly or indirectly forced to comply with Nazi racial preferences regarding who they employed or whose work was shown. The international impact was compounded by the wave of German artists and intellectuals – many of the Jewish – who were forced into exile, and their integration into cultural scenes in places like London and Paris acted to transmit knowledge of the nature of the Nazi regime. As such, Europe’s artists were among the best-informed about the nature of fascism, and became disproportionately involved in growing anti-fascist movements across the continent. As such, the wider anti-fascist mobilisation in response to the Spanish Civil War swept up Europe and North America’s cultural elite, whose direct or indirect knowledge of the conflict was a source of inspiration in the late 1930s. Not all of it has stood the test of time, but enough has.

One particular indicator of the cultural impact of the conflict came with a rather distinctive project undertaken by Nancy Cunard, who wrote to every prominent author she could think of with a short survey on Spain, soliciting their views. The 148 responses – from many of the most prominent literary figures of the day, from T S Eliot to Samuel Beckett – were overwhelmingly anti-fascist and pro-Republican. 16 professed neutrality, with just 5 proclaiming their support of Franco or fascism more broadly. In this sense, it’s unsurprising that the bulk of the most famous cultural responses to the civil war came from pro-Republican figures.

To answer your more specific question about censorship. Both sides had their own censorship regime, though through necessity, the Republican system was more open. The Republicans were the ones who needed to win over international support and sympathy, so went to great efforts to encourage neutral or sympathetic observers to visit and communicate the situation to a wider audience. Moreover, the Republic remained a meaningfully pluralistic society during the conflict, limiting the extent to which a complete curtailment of free speech was possible, and in fact the publication of newspapers, posters and other forms of cultural output blossomed in the Republican Zone to the extent that there was an endemic shortage of paper. This was the product of both widespread literacy programmes as well as a belief in the need to bolster civilian and military morale as a means by which material disadvantages might be countered. To be clear though, pro-Franco or otherwise anti-Republican cultural expression was restricted through censorship and more broadly through increasingly broad efforts to hunt real and imagined fifth columnists and spies in the rear, which had a natural dampening effect on anyone’s desire to speak warmly about the opposition. However, the Nationalist side not only had less need for the goodwill of international observers and journalists, its constituent political groups had no particular fidelity to an abstract notion of free speech or expression, meaning that a much more rigorous curtailment of art and media was both possible and desirable.