Chapter XII: Appendix: Explanation of Chart15

[15] [My readers will be as grateful as I am to Captain W.O. Barton,
lately at work at G.H.Q., for this vivid explanation of the Chart.]

THE CHART.--This Chart is a small scale reproduction of one used and corrected from day to day at British G.H.Q. in France. It shows graphically the actual position at any given date of the British forces in FIGHTING STRENGTH, FRONT HELD, and HEAVY GUN POWER: when big operations are in progress it gives at a glance the number of CASUALTIES incurred and PRISONERS taken, perhaps the surest indication of the measure of success gained. Owing to the size of the reproduction, the horizontal scale lines of the original Chart cannot be given. To calculate a number at any particular date from the Chart as reproduced, it is only necessary to measure with a rule the height of the desired line at the given date. Reference to the appropriate numerical scale at the side will then give the number.

1916, STRENGTH AND FRONT.--Begin with the FRONT and FIGHTING STRENGTH lines. The _Strength_ line tells the Commander his actual numbers (by reference to scale 2), but he needs more. He looks at the line representing _Front_ and marks the proportion it bears to _Fighting Strength_. Measure these lines in mid-June, 1916. Since January, FRONT (scale 1) has expanded by about one-fifth--from 67 to 90 miles. The Chart shows the reason. But meanwhile _Fighting Strength_, then the vital factor for attack, has risen from 470,000 to 680,000, nearly one-half. The Army has been built up by new Divisions for the great Somme offensive.

CASUALTIES.--The battle opens. The red line of casualties leaps into prominence and, with its ascent, STRENGTH falls. Reinforcements are needed. They arrive to replace casualties, and STRENGTH goes up again. So through the long conflict these lines act and react. Ground is won, but hardly and at great cost: the ascent of the Front line is slow.

PRISONERS.--What are the enemy losses? How are his men fighting? The PRISONERS line (scale 5) tells best. Gradually the proportion of prisoners to (British) casualties increases: his casualties are growing, his resistance becoming less effective: the wearing-out process tells. Mark the concluding phases of the Somme battle. The PRISONERS line is nearer to that of casualties. The Tank has been introduced, and here is ocular evidence of its effectiveness. More tanks is one of the lessons of the lines.

1917, ARRAS.--The Somme fighting ends. Again our armies are built up, until the 760,000 point is reached. FRONT, increased to nearly 120 miles by a relief of French troops, falls again to 105, owing to the German retirement about ARRAS. Heavy guns have increased from just over 300 to 1,500. Again our armies are ready, and the Battle of ARRAS opens the ALLIED SPRING OFFENSIVE. It is immediately effective, for casualties never reach the same height as in the Somme, and prisoners are much more numerous. The lines for the two battles show the difference vividly. But mark the big curve downward of the STRENGTH line. Casualties are now not so easily replaced.

MESSINES, YPRES, PASSCHENDAELE.--Before STRENGTH is fully restored the Messines ridge is rent with mines (June 7th) and taken. July is devoted to preparation: STRENGTH reaches its zenith, guns still increase, and on July 31st the Battle of YPRES opens the great northern offensive. Fighting is bitter, and more costly than at Arras; CASUALTIES are at first high in relation to prisoners, but the PRISONERS line, as in the Somme, but more consistently, tends upward. The German is not "sticking" the terrible conditions and fierce fighting so well as the Britisher.

CAMBRAI.--Then, in December, comes our surprise attack at Cambrai: it is effective, for PRISONERS nearly approaches CASUALTIES. LINE increases, owing to the salient formed by the British advance. Then, the _German_ counter-attack, with CASUALTIES high, PRISONERS few, and LINE decreasing. The Germans have reduced the salient made by our attack.

ITALY'S PLIGHT.--But meanwhile, the enemy has struck at Italy, and Italy, reeling under his blows, is clamant for aid. Division after Division hurries off! STRENGTH falls, never again to ascend. The handicap is permanent.

1918. With STRENGTH almost at its lowest since 1916, after a year of ceaseless fighting and heavy casualties, with five Divisions diverted to Italy, miles of FRONT have to be taken over from the French. Line held reaches its maximum, 130 miles. _Fighting strength_ has fallen by mid-March--when Divisions have been reorganised from 12 to 9 battalions, owing to the dwindling of reinforcements--to 580,000.

THE GERMAN THRUSTS.--The Chart has shown when we might attack. Now it gives the warning to expect attack. Now, if ever, is Germany's moment, and her first great blow falls on March 21st--the thrust at Amiens. CASUALTIES soar to a height never before approached. The red line predominates--STRENGTH falls and falls. Divisions are summoned from Italy and Egypt. The second German blow falls on the Lys. CASUALTIES are again immense, though not so high as in the first attack. STRENGTH falls again. The Lys salient increases the line held, but by the end of May the Line is firm throughout. Some few thousand Americans for a time reinforce the war-weary British Divisions; but the Portuguese cease to be reckoned in our _fighting strength_, though still in France. Reorganisation follows. STRENGTH is built up a little, though CASUALTIES are still heavy. The IXth Corps is fighting fiercely on the French Front to stem the Paris Thrust in May, and four British Divisions help in Foch's July counter-thrust. Guns, despite our losses to the enemy, have again increased. Guns are now more easily replaced than men.

THE FINAL PHASES.--Then the final phase. With decreased FIGHTING STRENGTH but with abundant GUNS (and, be it added, Tanks), we strike our first great blow in the Battle of Amiens on August 8th. STRENGTH falls abruptly, CASUALTIES are many, but high above the casualty line soars--for the first time--the line of PRISONERS. The toll taken of the German armies increases, as Bapaume and the Scarpe swiftly follow Amiens.

THE VITAL LINE.--Now the PRISONERS line has become vital. Consider the position in December before what is, perhaps, the decisive battle of the world war, the breaking of the Hindenburg line. GUNS are ever increasing, LINE has fallen somewhat, but lower even than in the dark days of spring has fallen the line of FIGHTING STRENGTH. To the General, studying this line alone, attack upon a position vaunted as impregnable would seem sheer madness. But he sees the Chart as a whole, with the PRISONERS line dominating everything in its sustained height. The enemy's total casualties are incalculable; never have ours been so few in comparison with prisoners taken: the hammering of previous years has borne fruit: the German _morale_, such is the lesson of the line, has gone irretrievably.

THE GREAT DECISION.--So, despite his own weakness, despite heavy losses not made good, the Commander takes the great decision and stakes all. He strikes, lets loose the tempest of his guns, and his infantry, diminished but indomitable, sweep through the vast fortresses of the Hindenburg line, hurl the enemy from defence after defence, pass from victory to victory.

Such is the story of the Chart.