Question

to prevent the us from resupplying allied forces, germany used a tactic known as continuous targeted ground strikes unrestricted submarine warfare rapid - fire bombing raids air - to - air combat

Explanation:

During World War I and II, Germany used unrestricted submarine warfare to disrupt Allied supply - lines, including those from the US. This involved attacking merchant ships without warning in an attempt to cut off supplies to the Allies.

Answer:

unrestricted submarine warfare