Simplify the following text for a Grade 13 native English-speaking person.
Original: In the spring of 1918 , in reaction to the growing repression of all opposition and free expression , the anarchist groups within the Moscow Federation formed armed gangs , the Black Guards , and Lev Chernyi played an active part in these .
Simplified: In the spring of 1918 , the anarchist groups within the Moscow Federation formed armed detachments in reaction to the growing repression of all resistance and free expression .