On 19th July 1936, the working class of Barcelona and Madrid succeeded in defeating the army and repelling the fascists in their attempt to take over Spain. It marked the beginning of an anarchist revolution, the lessons of which remain relevant 75 years later.
There are numerous accounts and analyses of the revolution's successes and failures in print and on the internet. This article from Do or die at the 70th anniversary provides a succinct overview, whilst An Anarchist FAQ goes into considerably more depth from a theoretical standpoint. The pamphlet Towards a Fresh Revolution, written by the Friends of Durruti in 1938, offers a radical position from in the midsts of the war as it raged on.
However, to mark the anniversary, I would like to draw people's attention to the documentary Living Utopia: The Anarchists and the Spanish Revolution. Featuring personal testimonies from numerous anarcho-syndicalist militants who took part, it is in my view a fitting way to mark this anniversary of a significant milestone in revolutionary class struggle.