Final answer:
The primary weapon used in antisubmarine warfare (ASW) is the torpedo.
Step-by-step explanation:
The primary weapon used in antisubmarine warfare (ASW) is the torpedo.
During World War I, German submarines, also known as U-boats, played a significant role in naval combat. German U-boats would sneak up on unsuspecting vessels and fire torpedoes to sink them. The use of submarines as a weapon in the war caused outrage and led to international tensions.