The original pack tactic envisaged that command and co-ordination would be exercised at sea; however while this had worked on exercise in the Baltic and North Seas it was unworkable in the wider reaches of the Atlantic. Hartman reported it was impossible to maintain an overview of the situation from his U-boat in the midst of the ocean and equally impossible to maintain contact with his charges.[2] The experience was also soured by the continuing torpedo problems that the U-boat Arm suffered during the first years of the conflict.