Russian narrative today is that Donbas somehow voluntarily split of Ukraine because it was overwhelmingly pro-Russian, but this is not true. There were pro-Ukrainian marches in Donbas as late as in March 2014 (presented here), long after annexation of Crimea. The only reason why they stopped was the arrival of Russian armed forces led by Igor Girkin on the night 12-13 April 2014 who started literally jailing and executing any people showing pro-Ukrainian views, starting with murder of Volodymyr Rybak.