For the American side, I nominate Major General Lloyd Fredendall, commander of the U.S. Second Corp in North Africa. Fredendall was responsible for the debacle at Kasserine Pass when he spread his units out so far apart that they couldn't support each other and had no overall commander so that each unit fought in isolation.
When his brilliant defensive plan was picked apart by Rommel, he panicked, came apart and had to be replaced. Fredendall was incompetent and a coward, at least in the view of his subordinates. He never went to the front lines and spent all his time in a headquarters built into solid rock that would have withstood a nuclear attack. His replacement was General George S. Patton, who everybody knew was crazy, but was at least an effective combat commander. So, we have that to thank Fredendall for, in that he advanced Patton's career.
Fredendall was sent back to the states to a hero's welcome, given a choice stateside assignment in charge of training, where he proceeded to train people in the wrong things and was even promoted to Lt. General before retirement.
Fredendall was a personal friend of General George C. Marshall ( Chief of Staff) and had been personally recommended for the Second Corp command by General Eisenhower.
Neither big names wanted to admit a mistake, and the public was not made fully aware of the nature of the defeat at Kasserine.
The battle was a blow to the morale of green U.S. troops in their first action and it took a while to restore confidence by the British in American troops. Patton started immediately to clean up the mess in his usual fashion.

Colonel Blimp... (QV the best film of WW2)

Originally Posted by papasha408

I may be reading the wrong military history but if I'm not mistaken the Japanese were pretty much out of ammo and either would have skulked off waiting for a way out of the peninsula or even surrendered themselves. Though the surrender part I never really believed. The Japanese commander bluffed his way to victory.

Yes you are absolutely correct about the Japanese lack of ammunition on hand, and yes he bluffed Percival into surrendering. I don't however see General Yamashita Tomoyuki surrendering or looking for a way off the peninsula. I think he would have simply waited until fresh supplies arrived. As the Japanese had total air supremacy I cannot see Percival counter attacking, all he could possibly do was shell Japanese positions with the 25 pounders available at that time.

Adolf Hitler constantly ignored his generals and was very arrogant and thought little of a break out at stalingrad which would cost him the war. Stupid decisions in the atlantic and in Britain too were disgraceful, he probably should of left italy to fight britain in africa while he fought the USSR and shouldnt have declared war on america. Not to mention the fact that he once again could of won the war if he didnt get army group centre to encircle the Kiev pocket and just gone straight for Moscow. Then after Kiev he took over Army group Centre. We should be happy he was so stupid.

Rather a simplistic view of WW2 don't you think?

This (simplistic) is one of the biggest euphemisms of 2014.

1) Hitler decided that the ME-262 be turned into a bomber in 43 which ruined the jets potential to win the skies for Germany over all fronts, which it might have done at that point in the war. When the jets were finally reverted to fighters in mid 44 they didn't have the fuel or the runways and as result there contribution was negligible. Never the less they fared extremely well against the allied pilots that did face them.

2) Hitler's no retreat orders was not the sole determining factor for many of the disasters' that befell the Germans but it did accelerate their defeat. The Germans strength was in tactics and mobility. Hitler never fully appreciated this in defensive operations from 43 on. Usually by the time Hitler allowed a retreat the heavy weapons had to be left behind and the withdraw took place in a desperate manner, due to it's last minute nature,
i.e. Crimea, Falaise.

Reason: Operation Goodwood, various other suicidal attacks on Caen and Market Garden

Originally Posted by JOC

Reason: Operation Goodwood, various other suicidal attacks on Caen and Market Garden

Personally I would go with someone like the Russian Marshal of the Soviet Union Grigory Kulik, the man was an incompetent bully who single handedly held back the modernisation of the Red Army.

An honorable mention should also go to Mark Clark for his post Anzio actions.

Originally Posted by MontyB

Personally I would go with someone like the Russian Marshal of the Soviet Union Grigory Kuli, the man was an incompetent bully who singlehandedly held back the modernisation of the Red Army.

An honorable mention should also go to Mark Clark for his post Anzio actions.

So many choices, Clark is a good runner up. Along with Stalin's crony Semyon Budenny.