Why did Germany abandon the "Sussex Pledge?

As the war progressed, Germany had more and more self-confidence.

Explanation:

Even before 1917, Germany extended its treaty with the United States. At that time, the united states threatened Germany, which withdrew, and German diplomats pointed out that the incident would not happen again. As the war progressed, Germany had more self-confidence. They believed that a total submarine war could defeat their suburbs as the united states became involved in the war.

is there options? or is it random words?

explanation:

answer; taking up arms to defend the nation;