Meanwhile efforts had been made to increase the strength of the Dover force, and by the end of June it stood at 4 flotilla leaders, 29 modern destroyers (including "Tribal" class), 10 old 30-knotters, and 6 "P" boats. The increase in strength was rendered possible owing to the relief of destroyers of the "M" and "L" classes at Harwich by new vessels recently completed and by the weakening of that force numerically. The flotilla leaders were a great asset to Dover, as, although they were coal-burning ships and lacked the speed of the German destroyers, their powerful armament made it possible for them to engage successfully a numerically greatly superior force. This was clearly shown on the occasion of the action between the _Broke_ and _Swift_ and a German force of destroyers on the night of April 20-21, 1917. The flotilla leaders on that occasion were, as was customary, patrolling at the Dover end of the cross-Channel barrage. The enemy's destroyers were in two detachments. One detachment, consisting apparently of four boats, passed, it was thought, round the western end of the barrage at high tide close to the South Goodwin Buoy, and fired a few rounds at Dover. The other detachment of two boats went towards Calais, and the whole force seems to have met at a rendezvous prior to its return to its base. The _Broke_ and _Swift_ intercepted them on their return, and after a hot engagement succeeded in sinking two of the enemy vessels, one being very neatly rammed by the _Broke_ (Captain E.R.G.R. Evans, C.B.), and the second sunk by torpedoes. Some of the remaining four boats undoubtedly suffered serious damage. Our flotilla leaders were handled with conspicuous skill, and the enemy was taught a lesson which resulted in his displaying even greater caution in laying his plans and evincing a greater respect for the Dover force for many months. The success of the _Broke_ and _Swift_ was received with a chorus of praise, and this praise was undoubtedly most fully deserved, but once again an example was furnished of the manner in which public attention becomes riveted upon the dramatic moments of naval warfare whilst the long and patient labour by which the dramatic moments are brought about is ignored. Thus in this case, but little attention was drawn to the years of arduous work performed by the Sixth Flotilla in the Straits of Dover by day and by night, in dense fogs, heavy gales and blinding snowstorms, in waters which were constantly mined, and in the face of an enemy who was bound to be in greatly superior force whenever he chose to attack. Little thought was given either to the wonderful and most gallant work carried out by the drifters of the Patrol, manned largely by fishermen, and practically defenceless against attack by the German destroyers.