Editing Battle of Passchendaele (section)

===British plans===

Preparations for operations in Flanders began in 1915, with the doubling of the Hazebrouck–Ypres rail line and the building of a new line from Bergues to Proven, which was doubled in early 1917. Progress on roads, rail lines, railheads and spurs in the Second Army zone was continuous and by mid-1917, gave the area the most efficient supply system of the BEF.{{sfn|Henniker|2009|p=273}} Several plans and memoranda for a Flanders offensive were produced between January 1916 and May 1917, in which the writers tried to relate the offensive resources available to the terrain and the likely German defence. In early 1916, the importance of the capture of the Gheluvelt plateau for an advance further north was emphasised by Haig and the army commanders.{{sfn|Edmonds|1991|pp=3–4}} On 14 February 1917, Colonel [[Norman MacMullen]] of GHQ proposed that the plateau be taken by a massed tank attack, reducing the need for artillery; in April a reconnaissance by Captain [[Giffard LeQuesne Martel]] found that the area was unsuitable for tanks.{{sfn|Edmonds|1991|p=25}}

On 9 February, Rawlinson, commander of the Fourth Army, suggested that Messines Ridge could be taken in one day and that the capture of the Gheluvelt plateau should be fundamental to the attack further north. He suggested that the southern attack from St Yves to Mont Sorrel should come first and that Mont Sorrel to Steenstraat should be attacked within {{nowrap|48 to 72 hours.}} After discussions with Rawlinson and Plumer and the incorporation of Haig's changes, Macmullen submitted his memorandum on 14 February. With amendments the memorandum became the ''GHQ 1917'' plan.{{sfn|Edmonds|1991|pp=17–19}} A week after the Battle of Messines Ridge, Haig gave his objectives to his army commanders, the wearing out of the enemy, securing the Belgian coast and connecting with the Dutch frontier by capturing Passchendaele ridge, followed by an advance on Roulers and Operation Hush, an attack along the coast with a combined amphibious landing. If manpower and artillery were insufficient, only the first part of the plan might be fulfilled. On 30 April, Haig told Gough, the Fifth Army commander, that he would lead the Northern Operation and the coastal force, although Cabinet approval for the offensive was not granted until 21 June.{{sfn|Sheffield|2011|pp=227–231}}{{efn|After mutinies had begun in the French armies, the British cabinet felt compelled to endorse the Flanders offensive, in the hope that more refusals to fight could be "averted by a great [military] success". Haig wrote that if the Allies could win the war in 1917, "the chief people to suffer would be the socialists".{{sfnm|1a1=Millman|1y=2001|1p=61|2a1=French|2y=1995|2pp=119–122, 92–93, 146}}}}