The Third Battle of Ypres is infamous for the deep mud that hampered infantry movement and artillery support, turning it into a disaster. The battle began with a deep offensive push led by General Hubert Gough's Fifth Army, but after the initial advance, a major tactical error was made that exacerbated the already terrible conditions.

Which of the following describes the specific tactical mistake made by the British High Command that directly resulted in the severe destruction of the local drainage system, which turned the heavy rains into a devastating, inescapable quagmire?