The armies under British command suffered some 275,000 casualties at Passchendaele, a figure that makes a mockery of Haig’s pledge that he would not commit the country to "heavy losses.” Among these were 38,000 Australians, 5,300 New Zealanders, and more than 15,600 Canadians; this final figure was almost exactly the total that had been predicted by Currie ahead of the battle. The Germans suffered 220,000 killed or wounded. At the end, the point of it all was unclear. In 1918 all the ground that had been gained there by the Allies was evacuated in the face of a looming German assault. Passchendaele would be remembered as a symbol of the worst horrors of the First World War, the sheer futility of much of the fighting, and the reckless disregard by some of the war’s senior leaders for the lives of the men under their command.
https://www.britannica.com/event/Battle-of-Passchendaele