I'm not sure if I agree with that. > Describe the events up to WWII For me that sounds like you would include WWII, just like if you counted up to 20. > Desc

I'm not sure if I agree with that. > Describe the events up to WWII For me that sounds like you would include WWII, just like if you counted up to 20. > Describe the events leading up to WWII Then I would agree, that would be "explain the set of events on which WWII depended" so that would include all prior events which are relevant to WWII, without including WWII itself, but also missing out any events not relevant to WWII, so not e.g. "OK so the ice age was before WWII, so let's start there". (Native English speaker, from UK).