In Ruhrkampf, Barthel Gilles (1891-1977) portrayed a battle that took place ten years earlier in the Ruhr industrial area between radical workers and the regular army and police. The workers had been on strike and were suffering terrible repression - they eventually turned to arms for self defense. Fighting soon broke out with the authorities and escalated to civil war proportions. The workers were defeated by the army and police only after hundreds of workers had been killed. Gilles was a member of the German Communist Party (KPD) and during the Nazi era was prohibited from painting or exhibiting his work publicly. (http://weimarart.blogspot.nl/2010/05/barthel-gilles-ruhr-battle.html)