What were two ways the u. s. navy countered the u-boat threat?

1. using the convoy system where destroyers escorted transport ships across the Atlantic

2. beginning in June 1918, the Allies began laying a barrier of 70,000 mines in the North Sea, making U-boat access to the North Atlantic virtually impossible.

With the convoy system, large trade ships were boxed in by cruisers so if there happened to be an attack these ships could attack back. Since Germany attempted to block any trade at this time, the convoy system was essential to continue trade with Europe.

Explanation:

they united the colonies in their fight against the british.

bless you your highness