Complex sentence: The defenders (private forces) were no match for the crowd (who were thus removing an unlawful obstruction) and the event was contemporaneously dubbed the Moor Park Riot or the Battle of Moor Park.
Split into simpler sentences: The defenders (private forces) were no match for the crowd (who were supporting the removal of an unlawful obstruction). The event was dubbed the Moor Park Riot or the Battle of Moor Park.