What was the most significant use of german submarines during world war i?

The german sumbarines were used to sunk ships carrying enemy supplies such as oil , flod etc. On the 17th of March, the German submarines had been able to sink three of the American merchant vessels, and due to this the U.S. had declared a war on the Germany army in the month of April in 1917.

the great wall of china worked as a defense for the feudal states of the zhou dynasty to the north. during the warring states period more walls were put up to defend the borders of the different kingdoms. it was semi successful because despite the wall, the mongols eventually conquered china also the great wall provided protection to the economic development and cultural progress, safeguarded the trading routes such as the silk road, and secured transmission of information and transportation. @jayxboof

gays

explanation: