What major national-level development happened in the late nineteenth century?

There were many national level developments in the late-nineteenth century. Perhaps the most important was the development of the light bulb by Thomas Edison. Edison's invention revolutionized all aspects of American life ranging from work to leisure. It also inaugurated the modern electrical industry.

explanation:

aids

it was the "4. potsdam" conference that demanded the unconditional surrender of japan, since it was clear that the japanese would continue to find until the very last man otherwise.