The period from when the Somme battle officially ended to operation Alberich, the German retreat to the Hindenburg Line
This talk argues that the BEF could (perhaps even should) have made major gains during Third Ypres but that the battle bogged down NOT because of the mud but because of very poor BEF engineering organisation
IMAGE: Battle of Menin Road. "Australian wounded on the Menin Road, near Birr Cross Road on September 20th, 1917". (Caption source: National Library of Australia, n.d. (1 June 2014).