About the coalitions, John S. D. Eisenhower says:
Yet in the case of High Command in France, another factor had to be given careful consideration - feelings of national pride. Pride in country and tradition is not to be discouraged; a soldier cannot fight without it. But in the highest command echelons of nations that have combined their resources to fight a common enemy, this feeling must often be subordinated to the goo of the whole.
This is not easy. Napoleon's detractors have pointed out that his brilliant campaigns were fought largely against coalitions. The coalition between the British and the Americans in World War II was not automatic, It could be injured, conceivably fatally, despite the fact that the two national political leaders were joint signatories of the Atlantic Charter and despite the intense admiration that Americans felt for Britain as she stood alone in 1940. For this reason, General Eisenhower ruefully concluded when writing his memories in 1948, the concealment of projected command arrangements was a mistake,
Eisenhower, John S. D. The battle of the Bulge. Page 66.
Never in history was there a coalition like that of our enemies, composed of such heterogeneous elements with such divergent aims... Even now these states are at loggerheads, and, if we can deliver a few more heavy blows, then this artificially bolstered common front may suddenly collapse with a gigantic clap of thunder.
(upon the ordering the attack through the Ardennes)