Yup they are. They get you marks for "knowledge" which is a fair percentage of the exam. You will always need a "rough" idea of when the event took place so always know the year any event took place in but if it HUGE (start of ww2, fall of berlin wall etc) then I suggest remembering the month and perhaps the day.
Essentially - generally if you can say what year it was in and maybe month but most of the time you wont need the exact date.