In the winter of 1916–17 the German General, von Hindenburg, would lend his name to a battery of defensive fortifications which, by eliminating the salient south of Arras, reduced the German front line by 30 miles (50 km). This, the Hindenburg Line, released some ten divisions from defensive duties. Between February–March 1917, as they successfully retreated to the line, the Germans adopted a ‘scorched earth’ policy by poisoning wells, uprooting tree and laying mines to impede enemy forces. The line itself was up to 8 miles deep (13 km) and the deep forward trenches were planted with concrete machine gun emplacements. Operation Alberich (14 March–5 April 1917), the retreat to the new line, was accomplished with only minimal Allied interference: it would prove its worth within weeks during the Nivelle offensive.
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