supplementary to the work of the destroyers engaged
on the regular Dover Patrol, the indomitable Sixth Flotilla.

A great deal depended upon the work of these destroyers. They formed the
principal, indeed practically the only, protection for the vast volume
of trade passing the Straits of Dover as well as for our cross-Channel
communications. When the nearness of Zeebrugge and Ostend to Dover is
considered (a matter of only 72 and 62 miles respectively), and the fact
that one and sometimes two German flotillas, each comprising eleven
large and heavily armed torpedo-boat destroyers, were usually based on
Bruges, together with a force of large modern torpedo boats and a very
considerable number of submarines, it will be realized that the position
was ever one of considerable anxiety. It was further always possible for
the enemy to send reinforcements of additional flotillas from German
ports, or to send heavier craft with minesweepers to sweep a clear
channel, timing their arrival to coincide with an intended attack, and
thus to place the German forces in a position of overwhelming
superiority.

Our own Dover force at the commencement of 1917 consisted of one light
cruiser, three flotilla leaders, eighteen modern destroyers, including
several of the old "Tribal" class, eleven old destroyers of the 30-knot
class (the latter being unfit to engage the German destroyers), and five
"P" boats. Of this total the average number not available at any moment
may be taken as at least one-third. This may seem a high estimate, but
in addition to the ordinary refits and the time required for boiler
cleaning, the vessels of the Dover Patrol working in very dangerous,
foggy and narrow waters suffered heavy casualties from mines and
collisions. The work of the Dover force included the duty of escorting
the heavy traffic between Dover and Folkestone and the French ports,
this being mostly carried on during daylight hours owing to the
prevalence of submarine-laid mines and the necessity for sweeping the
various channels before the traffic--which included a very large troop
traffic--was allowed to cross. An average of more than twenty transports
and hospital ships crossed the Straits daily during 1917, irrespective
of other vessels. The destroyers which were engaged during daylight
hours in this work, and those patrolling the barrages across the Straits
and off the Belgian coast, obviously required some rest at night, and
this fact reduced