It only goes , howevere, to further Barone's comment..that it takes time to find the right commanders. FDR did NOT have them at the start. The first US effort in the war..the US landings in North Africa..led to a defeat, if not a rout at Kasserine pass. They took very heavy casualties, and the commander was relieved on the spot and sent home in disgrace. Of course, no one at home knew about it until several weeks had past, because of censorship and media cooperation.
A comparable example in Iraq would be if a Marine battalion at Fallujah had taken 50% casualties (KIA/WIA) over several days attempting to retake the city, and untimately failed and had to be pulled back. Imagine what would be going on...
In 1944, 8 Generals were reduced to permenant grade (Col/LTC) and sent home by Eisenhower for not being able to keep their mouth shut about D-Day plans. Fortunately, the Germans thought it was disinformation...
That was just in UK between Jan-Jun 1944.
Plenty of senior officers were relieved for cause in WWII. The military does not hide the fact but, it does not advertise it either...