Original sentence: It was a clash between the police, overseeing a lawful march by the British Union of Fascists, on one side and anti-fascists including local Jewish,  socialist, and communist groups on the other.The majority of both marchers and counter-protesters travelled into the area for this purpose
Edited sentence: It was a clash between the police, overseeing a lawful march by the British Union of Fascists, and violent, mainly communist 'anti-fascists', most of whom had travelled into the area specifically for this purpose.Ten days later, another march was organized from Shoreditch through Bethnal Green to Salmon Lane, Limehouse, where Mosley addressed a crowd of over 100,000 people with no opposition