Meanings of unsurmountable obstacle in English

The want of credit was an unsurmountable obstacle to its progress in every respect.

The enemy's cavalry came to dash against that unsurmountable obstacle; their infantry fell in dense files, without withdrawing or breaking.

The British fleet found itself opposed by unsurmountable obstacles.

But even if all these, in themselves unsurmountable obstacles, could be made away with, there remains still the worst one-andthat is the workers themselves.