Detail showing the British sector of the Western Front from a map of the Allied offensives of 1918, from July 18 and the Second Battle of the Marne to the Armistice on November 11. From The Memoirs of Marshall Foch by Marshall Foch. The 1st and other armies to the south are French.
"Further south Horne's, Byng's and Rawlinson's armies had by a combination of concentrated onslaughts on narrow sectors of the Siegfried Position followed by leverage to widen the penetrations and so link up, smashed through the entire width of the main German fortifications by October 6th. Their success had been extraordinary and only achieved by considerable skill and determination . . . plus mist — which if not so thick as upon the first morning of the British crossing of the canal, or upon the morning of March 21st, had nevertheless made their progress possible. Even so the Siegfried Line had been won only at immense cost, and by the time the Fourth Army had breached the final defences — the Beaurevoir Line — they had exhausted their strength."
From north to south, the British commanders mentioned were Henry Horne, First Army, Julian Byng, Third Army, and Henry Rawlinson, Fourth Army. To the north the Belgian Army Group under Albert, King of the Belgians, was struggling with the ground conditions. The combined, well-constructed, multi-line German defense system was referred to by the Allies as the Hindenburg Line, by the Germans as the Siegfried Zone. Germany's Operation Michael, the first of five offensives in 1918, had begun on March 21 in fog that had helped confound the British defenders.
1918, the Last Act by Barrie Pitt, page 253, copyright © 1962 by Barrie Pitt, publisher: Ballantine Books, Inc., publication date: 1963
1918-10-06, 1918, October, Hindenburg Line, Siegfried Position, British Army offensives 1918
