In January, the Spartacus League and others in the streets of Berlin made more armed attempts to establish communism, known as the Spartacist uprising. Those attempts were put down by paramilitary "Freikorps" units consisting of volunteer soldiers. Bloody street fights culminated in the beating and shooting deaths of Rosa Luxemburg and Karl Liebknecht after their arrests on 15 January. With the affirmation of Ebert, those responsible were not tried before a court martial, leading to lenient sentences, which made Ebert unpopular among radical leftists.