Johannes Gutenberg was a German blacksmith known for inventing the mechanical movable type printing press<span>. His </span>printing press<span> has been widely considered the most </span>important<span> invention of the modern era because it profoundly impacted the transmission of knowledge.
</span>Its immediate effect<span> was that it spread information quickly and accurately. This helped create a wider literate reading public.
</span>
They got to know with the photographs from the U - 2 spy plane.
<em>Hope this helped! :)</em>