In looking back over the last four years, the sharpest outlines in the retrospect are the ups and downs of hopes and fears. Indeed, so acutely must everyone bear these alternations in mind, that to remark on them is almost to incur the guilt of commonplace. For they illustrate the tritest of all the axioms of war. It is human to err--and every error has to be paid for. If the greatest general is he who makes the fewest mistakes, then the making of some mistakes must be common to all generals. The rises and reversals of fortune on all the fronts are of necessity the indices of right or wrong strategy. These transformations have been far more numerous on land than at sea, and locally have in many instances been seemingly final. Thus to take a few of many examples, Serbia, Montenegro, and Russia are almost completely eliminated as factors; our effort in the Dardanelles had to be acknowledged as a complete failure. But at no stage was any victory or defeat of so overwhelming and wholesale a nature as to promise an immediate decision. The retreat from Mons, Gallipoli, Neuve Chapelle, Hulloch, Kut--the British Army could stand all of these, and much more. France never seemed to be beaten, whatever the strain. Even after the defection of Russia, a German victory seemed impossible on land. Never once did either side see defeat, immediate and final, threatened. A right calculation of all the forces engaged may have shown a discerning few where the final preponderance lay. The point is that, despite extraordinary and numerous vicissitudes, there never was a moment when the land war seemed settled once and for all. This has not been the case at sea. The transformations here have been fewer; but they have been extreme. For two and a half years the sea-power of the Allies appeared both so overwhelmingly established and so abjectly accepted by the enemy, that it seemed incredible that this condition could ever alter materially. Yet between the months of February and May, 1917, the change was so abrupt and so terrific that for a period it seemed as if the enemy had established a form of superiority which must, at a date that was not doubtful, be absolutely fatal to the alliance. And again, in six months’ time, the situation was transformed, so that sea-power, on which the only hope of Allied victory has ever rested was once more assured.