of meeting the cruiser escorts at the appointed rendezvous,
and of dispersing them when the danger zone was passed;
and naval officers were systematically put in charge.
The convoys of this period were very large; from 200
to 300 ships were not an unusual gathering, and some-
times 500 or more would get together at certain important
places, such as the entrance to the Baltic. But these
ships, of course, were very small compared with those of
the present time. It was only necessary to supply such
aggregations of vessels with enough protecting cruisers to
overwhelm any raiders which the enemy might send
against them. The merchantmen were not required to
sail in any particular formation, nor were they required
to manoeuvre against unseen mysterious foes. Neither
was it absolutely essential that they should keep constantly together ; and they could even spread them-
selves somewhat loosely over the ocean. If an enemy
raider appeared on the horizon, the escorting cruiser or
cruisers left the convoy and began chase; a battle ensued,
the convoy meanwhile passing on its voyage unharmed.
When its protecting vessels had disposed of the attackers,
they rejoined the merchantmen. No unusual seamanship
was demanded of the merchant captains, for the whole
responsibility for their safety rested with the escorting
cruisers.
But the operation of beating off an occasional surface raider, which necessarily fights in the open, is quite a different procedure from that of protecting an aggregation of vessels from enemies that discharge torpedoes under the water. As part protection against such insidious attacks both the merchant ships and the escorting men-of-war of to-day had in this war to keep up a perpetual zigzagging. This zigzag, indeed, was in itself an efficacious method of protection. As already said, the submarine was forced to attain an advantageous position before it could discharge its torpedo ; it was its favourite practice to approach to within a few hundred yards in order to hit its victim in a vital spot. This mere fact shows that zigzagging in itself was one of the best methods of avoiding destruction. Before this became the general rule, the task of torpedoing a vessel was comparatively easy. All it was necessary for the submarine to do was to bring the vessel's masts in line; that is, to get directly ahead of her, submerge with the
