In 2011, Sheffield wrote that the new German defences built behind the third position in the onset of autumn required a series of bite and hold attacks, which were beyond the ability of the British to arrange in time to reach open country. In late September, Haig had ordered an ambitious three-army offensive operation toward Cambrai but despite showing increasing tactical skill and inflicting many losses on the Germans, the territorial gains were "miserly". Haig persisted because he believed that attrition was working, the British Expeditionary Force was improving and that he overestimated the capacity of the armies in a wet and muddy season. The pressure from Joffre to continue was also significant and Haig wrote sympathetically of Cavan's protest in November but that the French could not be left in the lurch. In late October Haig reminded Joffre that although subordinate to French strategy he retained discretion over the operational and tactical matters of where, when and how.