Prelude

The Spanish Civil War was perhaps the most influential event of the 1930s, and possibly the whole 20th Century. The rise of Francoist Spain and the defeat of the Republicans would have long-lasting ramifications. Arguably, Hitler would have been less inclined to invade France without a Fascist ally to her west. The Soviets would have a strong ally in Europe, and the Cold War (if it even happened) would be much different. However, perhaps the most decisive result of the Spanish Civil War was that Socialism was crushed in one of its earliest and most promising cradles. Had it not been for the authoritarian Franco regime, we might very well be looking at a Red Spain, and possible a Red France.
It is wrong to assume though that Republicans never had a chance. In fact, the majority of Spanish people supported the Republican government, and at the outbreak of war and the coup attempt by the Nationalists, Spanish people, especially those in Catalonia and the Basque county, helped stopped the rebels from taking control. If it were not for Franco's massive airlift of troops from Morocco brought about mostly by Hitler's German Luftwaffe, it is very likely that the rebel lis would very likely have been crushed in a matter of months or even weeks, at least on the mainland. In fact, the most decisive factor in the outcome of the war was foreign aid from Germany and Italy into the Nationalist cause, and the lack of it from the Republic's allies. Before Hitler had ever invaded Poland, he had won himself a war in Spain.
The main Nationalist battle flag
These are not the only things that make the Spanish Civil War so intriguing though. During the course of the war, arguably the most successful Socialist communes were set up in Catalonia and Aragorn. These communes, run mostly by the principles of anarcho-communism and organizations like the CNT and POUM, were very effective in their collectivization of farms and businesses. Unlike in many European Civil Wars, these communes never ran out of food and supplies to take care of their forces, and put up the stiffest resistance to the Nationalists in all of Spain, save for the armies in Madrid. These communes drew a substantial amount of foreign volunteers, most notably George Orwel (who narrated his experiences in his book "Homage to Catalonia"), Norman Bethune, and the mostly American and Canadian Abraham Lincoln Brigade. Orwell would later recount that his time in the Catalonian commune would shape his political views of anti-Stalinism (Stalinists frequently fought with the Anarcho-Communists for control) and would be a major influence on his book 1984; however, these experiences also proved to him that Socialism can work and that it is best achieved through democratic means with the people making decisions, not totalitarian dictators.
The flag of the Republican Popular Front
Our POD in this ATL is a combination of three events. First, the French government pressures Germany into giving less foreign aid to the Nationalists by threatening extreme economic sanctions, causing the German airlift of Franco's Morocco regiment the be severely depleted. Second, the Republican government, seeing as many of its chief military officers have defected to the rebels, decides to arm and train the Anarchists and local left-wing militias. Third, the Anarchists and Republican government forces focus on building up the defenses near cities like Navarre and Pamplona rather than trying to purge the Republican territories of Catholic clergy and conservatives, in turn earning the government forces greater support among Spanish people in places like the Ebro Valley and Bilboa.
So, without further ado, I present to you the "revolutionary" new Spanish Civil War timeline:
Battle Hymn of the Republicans
A Republican militia advancing on Nationalist positions outside Madrid