when world war ii began, "friedrich ihn" was initially deployed in the baltic to operate against the polish navy and to enforce a blockade of poland, but she was soon transferred to the german bight where she joined her sister ships in laying defensive minefields. she also patrolled the skagerrak to inspect neutral shipping for contraband goods in october. the ship was scheduled to conduct a minelaying operation off the british coast in early november, but it was cancelled when one of the other destroyers assigned to participate suffered machinery problems from contaminated fuel oil.