For the same reason it was necessary that we should protect them, and we did this as far as practicable without causing undue delays in forming outward-bound convoys. The _Justicia_, though most people still think that she was torpedoed because she was unescorted, was, in fact, protected by a destroyer escort of considerable size. This duty of escorting outward-bound ships increased considerably the strain on our destroyer force. The difficulty was that the inbound convoy arrived in a body, but that the ships could not be unloaded and sent back in a body without detaining a number of them an undue length of time--and time was such an important factor in this war that it was necessary to make the "turn-around" of each important transport as quickly as possible. The consequence was that returning ships were often despatched in small convoys as fast as they were unloaded. The escorts which we were able to supply for such groups were thus much weaker than absolute safety required, and sometimes we were even forced to send vessels across the submarine zone with few, if any, escorting warships. This explains why certain homeward-bound transports were torpedoed, and this was particularly true of troop and munition convoys to the western ports of France. Only when we could assemble a large outgoing convoy and despatch it at such a time that it could meet an incoming one at the western edge of the submarine zone could we give these vessels the same destroyer escort as that which we always gave for the loaded convoys bound for European ports.