Question

What was the most significant use of German submarines during World War I?

Answer 1

the german sumbarines were used to sunk ships carrying enemy supplies such as oil , flod etc.

Answer 2

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 Unrestricted submarine warfare in the early 1917 had been initially very successful.

It was sinking a major part of the Britain-bound shipping.