I could not understand the part " in the face of this onslaught" in the following passage.
Mathematics developed as a response to the demands of the sciences, which grew up in the late sixteenth century. The thinkers of the early Scientific Revolution had provided their descendents with a broad framework of new philosophies, hypotheses, and qualitative observations, all of which pointed to a revolution in thought. However, the old order was at first easily preserved in the face of this onslaught, in part due to the lack of substance to back up the theories of such thinkers as Nicolas Copernicus and Giordano Bruno. Though these scientists sensed that their hypotheses were correct, and strongly believe in them on their own, it was difficult to bring their theories to the position of respect they deserved without the benefit of clear and logical evidence.
In the face of means
1.When confronted with:
her resolution in the face of the enemy
reform had been introduced in the face of considerable opposition More example sentences
1.Fierce or destructive attack:
a series of onslaughts on the citadel More example sentences
1.1 An overwhelmingly large number of people or things:
in some parks the onslaught of cars and people far exceeds capacity
Could you please explain whole sentence to me?