Why German forces would still reveal activity by radio

Would German forces use land telegraph lines instead of revealing their movements by radio?

They would still use radio because moving formations could outrun the telegraph network, and even ships in harbor received wireless orders.

Land maneuvers could carry forces beyond telegraph lines already laid, leaving radio necessary for coordination. Ships also received broadcasts from Berlin while still in harbor. Scheer used different call signs ashore and at sea, providing another potential clue to a fleet movement. These examples explain why British intelligence could learn from German communications activity before reading the contents of a message.