[Paul1980au]

ANother way is to have a big invasion fleet (go after his home system) if he has say 6 planets (small) and the main one invade the six small ones in one turn - demand the surrender - he usually surrenders.

Or another sneaky way is to say he has 4 systems - intel where his spaceports are - attack those planets - that reduces his capacity to generate any resources or research or anything - his fleet becomes less maintainable and he should surrender.

Just make sure you rebuild them as soon as possible or have the racial ability where you dont need spaceports.