The germanic tribes were able to invade britain because the crumbled.

The Germanic tribes were able to invade the Britain because of the western half has crumbled by which they were able to push the Romans out, where in, Romans has taken hold of the Germanic people and by pushing them out, they have the power to invade the Britain.

the catholic church withhold people's access to the bible during the middle ages.

people could go to church and listen to the teachings, but it was absolutely forbidden to own and/or read the books of both the old and new testaments. it was also prohibited to translate the books (which where originally in biblical hebrew) to any other language.

this was done so the church could remain in control of what their teachings were and to enhance their importance and power, while also being able to judge people's actions through information that was unavailable for the general public.