Bernard Law Montgomery is a general who is much malined but Armchair Generals and historians for being successful against an adversary with less manpower and supplies than he had and for being a concieted, arrogant egomanic yet often these same people who criticize Monty for these traits will praise Patton and justify their praise by white-washing over the issue of manpower and material superiority that Patton likewise enjoyed.
There are some ridiculous double standard displayed when Monty is involved.
For example, when Erwin Rommel beat the British time and again in North Africa with the advantage of better weaponry and better intelligence it was because he was genius but when Monty beat him it was only because he had better intelligence and the edge in manpower. In the one instance a general is praised as a genius for taking advantage of the better weapons and better intelligence at his disposal but in the other case the general is considered poor for the reason that he only won because of having the advantage in manpower and intelligence.
Monty's first task in North Africa was to reorganize and retrain the 8th Army and did so within a matter of weeks. He still had creases to iron out though. The Armour commanders had remained basically the same and they had suffered long campaigns against Rommel and were now afraid to take risks. Before Alam Halfa Monty was greatly annoyed at Herbet Lumsden for suggesting the Armour be used like cavalry and prevented him from playing a bigger part in that battle - it was Lumsden's attitudes toward Armour that convinced Monty that any persuit of the German Armour by British Armour was likely to be a failure - then he was further annoyed with Lumsden during 2nd El Alamein as he exersized a weak hold over the other Armour commanders and a timmidity that let the New Zeelander's and Austrailian's efforts go to waste.
While the manpower superiority did play a crucial part in the victory at El Alamein it was not as decisive as it has been made out to be. To get to the Afrika Korp Monty's 8th Army had to first find its way through the biggest minefield laid in the entire war and then try to assail the most fomidable defensive position yet seen the conflict. By definition 2nd El Alamein was a meatgrinder of a battle and would have been such had any commander been in Monty's shoes.
His persuit of the Afrika Korp after the victory at 2nd El Alamein was relentless and swift. The 8th Army advanced across the desert in 720 miles in 20 days. When Rommel turned attention back to the British after giving the Americans a bloody nose at Kesserine Pass he engaged Monty at Medenine but Monty made excelent use of the intelligence at his disposal to counter Rommel's attempted attack and deliver a stiff defeat to the Desert Fox.
Monty went on from that victory at Medenine to defeat the Axis forces once more at the Mareth Line but Rommel was no longer there, he had been sent home after his latest defeat to Monty.
The Sicily campaign is an interesting one that is usually full of nationalistic pride. Much of that nationalistic pride is the fault of Patton and Bradley. It's Patton's fault originally as seeing the Campaign as a chance to upstage Monty and beat him in a race and Bradley's fault for perpetuating this nationalist pride arguement through his influence in the film "Patton".
While it is true that Monty changed the lines of advance and muscled into Bradley's area and Patton reached Messina before Monty there are some important bits that's missed out. For example, Patton decided that, rather than fight the Germans as the other Allied forces were doing he was going to go for the glory of capturing Palermo and after advancing against no opposition he took the city and decided his work was done. As Monty fought his way forward against the Germans he realized that Alexander was not trying to control the campaign and felt the need to get involved and he did this but suggesting to Alexander that Patton be sent to take Messina.
While the Sicily showed both Monty and Patton as arrogant egomanics it also showed Monty's abilities to work with his allies and to find solutions where others failed. He gained a reputation with the American commanders during this campaign for being concieted and arrogant but a thoroughly good soldier and general.
Monty thereafter commanded the 8th Armies advance up Italy but was frequently frustraited by the lack of allied cooperation. After breaching the Gustav Line but being unable to exploit that breach due to bad weather he recieved news that he was being transfered to Britain to command the Ground Forces during the Normandy Invasion.
Monty changed the plan for Operation Overlord from a two beach landing followed by a single thrust toward Cean then a sweep towards Cherburg before turning back East to a five beach landing followed by a holding action by the British on the left allowing the Americans to liberate the vitally important port of Cherburg and then the Britanny ports and turn the German flank. In broad strategic sense this is what happened when the battle took place, only tactal changes were required as the battle progressed. Monty insisted on close cooperation between Allied forces during the invasion as the invasion of Sicily and Italy had been poorly inter-coordinated, poorly managed and suffered as a result. Even his more ardent critics say that Normandy could not have happened without Monty.
There are other factors to concider in the Normandy Camaign. For example Air Marshall Arthur Tedder's documented attempts to not only undermine Monty but also Trafford Leigh-Mallory and to create several potential disastor in Normandy where there were none to support his opinion that Monty and Leigh-Mallory needed to be replaced. Tedder essentially spent the entirity of that campaign niggling at Eisenhower and trying to convince him that everything was going wrong and Monty and Leigh-Mallory should be replaced by the two of them.
Monty then often gets accused of being slow in Europe but this flies in the face of fact. In reality Monty advanced just as fast as the American's did across Europe and oft times was covering more ground per day than the American forces were, with equal and sometimes heavier forces at his front.
Market Garden was his one big failure but even so it was not a defeat in the most technical of terms. It was a failure in terms of the lost opportunity it represented but it was neither a set back nor a check. It was over ambitious and poorly handled and thus failed. He then was forced to turn and deal with the Scheldt esturaries where he had underestimated the effort needed to clear it.
At the Bulge what he said of his impact was true in the bluntest sense of the words. While tactfully laking he spoke the truth when he said the American's had lost control of the Northern sector of the battle and Ike had place him in charge to clean up the mess. His impact was to turn a serious of isolated and uncoordinated battles of American units into a coherant battle fought to a clear and definiative plan - it was the tactless way he spoke of it afterwards that made people angry, particularly Bradley and Patton who were both involved in their own private rivalry with Monty (one Monty knew nothing about at the time).
To summarize, Monty was the foremost soldier of the British Empire in the western world. There was nobody better suited of better qualified to command a British Army than him. He was ruthless, he was determined and he was relentless in everything he did, from teaching to commanding armies in the field. He was however a tactless man, conceited and arrogant with an enormous ego and a superiority complex.
In a sense of pure military abilty and success as a general Monty ranks easilly in the top 10 generals of WWII, possibly even braking the top five, but in terms of abilities to create command harmony at all levels he rates easilly in the bottm 10.