Mixed brigade was a basic tactical military unit of the Republican army during the Spanish Civil War. It was initially designed as "pocket division", an innovative maneuverable combined-arms formation. Because of high saturation with specialized troops and services it would have resembled a division, but in terms of manpower it would have been much smaller and amount to some 3,700 men.

The confederal militias were a movement of people's militia organized during the Spanish Civil War by the dominant organizations of anarchism in Spain: the National Confederation of Labor (CNT) and the Iberian Anarchist Federation (FAI).