Interstellar Patrol

The starship crew was stuck on a planet where the well-meaning schemes of social engineers had created a nightmare of battling gangs. So they pretended to be the Royal Legions from a distant star kingdom pursuing an all-powerful villain hiding on the planet. Things went better than they could have hoped, and the planet was rapidly becoming civilised...and then the real Royal flagship showed up. They thought they were doomed - but instead they had shown just the type of initiative and intelligence that the new arrivals were looking for. So they were inducted into the Interstellar Patrol. And that was just the beginning...