I’ve known a number of American WW2 vets who survived, some of them barely, because of Montgomery’s arrogance and recklessness. They hated him.
Montgomery is an interesting study in competence losing to hubris due to success. He was actually probably the best general the British had from the start of hostilities through the effective ejection of the Axis from Africa. The retrograde action of his 3rd Division back to Dunkirk after advancing to the Dijle and realizing they couldn’t hold their gains (and that they had no support) is a textbook example of the results of proper prior training and planning even when everything else has gone to hell. It was also remarkable in how few casualties they sustained for the damage caused to the advancing German horde and how the division survived almost completely intact all the way back to England - despite seeing serious action. It was clear that he was realistic, cared for his men and had a good grasp of his own limits at this point in time.
He went on to be a solid and methodical commander in Africa and while not spectacular, he did the job well. His guiding principle of not going on the offensive until you had as overwhelming a force as you could muster in a timely fashion is still a solid one today and it served the Allies well in Africa.
Unfortunately at this point, the British press began massively promoting the man’s actions and comparing him to Nelson or Wellington. Even more unfortunately, he began *believing* that he was that good. From this point forward, he was increasingly a glory hound for himself and for his empire, over and above the good of his men and the actual goals of the war. He became increasingly convinced that he could do no wrong and that his plans would always succeed. We’ve already seen how that worked; Market Garden was insanely complex and relied on too many moving parts working and moving at exactly the right time with not enough margin given for, say, enemy action, environmental variables or just plain bad luck. The plan seems to have been to get the Empire (and Monty) the most glory and more important in the short term, more influence in the conduct of the war in the European theatre. Troops paid the price for his and his government’s machinations.
Montgomery in 1940 is just the kind of guy you want covering your arse in a retreat, keeping the enemy off you while husbanding his men and equipment well. Montgomery in Africa is the guy you want running the show to keep your troops alive and to extract maximum gains for minimum loss while not giving an inch.
Montgomery after Africa is someone you increasingly really don’t want to be anywhere near. Or worse, under, with the decay of his effectiveness and increase in arrogance starting in Sicily. Fortunately for everyone else in the Allied forces, Market Garden was rightly the end of *that* particular crapshow of a policy and a general from the British.