"These people who say the wrong thing aren't necessarily bad people or inherently mean people, they just all of a sudden step over the line," he said. "They just slip into arrogance under stress."
Such arrogance has been on display before among U.S. generals and the results have almost always been the same.
President Abraham Lincoln famously fired Gen. George McClellan during the Civil War in 1862 after he reportedly referred to the president as a "well meaning baboon."
And in 1951, President Harry Truman fired Gen. Douglas MacArthur after the general, whose popularity outranked the president's at the time, publicly criticized Truman's handling of war strategy.
Truman later told biographer Merle Miller that he fired MacArthur because "he wouldn't respect the authority of the President."
Gen. Eric Shinseki angered the Bush White House when he testified before Congress it would take hundreds of thousands of troops and a lot more money to invade Iraq than Defense Secretary Donald Rumsfeld was allocating to the war. Shinseki wasn't fired, but White House displeasure is widely believed to have led to his resignation.