At that point at which McClellan is summoned from Western Virginia to serve in the East, Winfield Scott is a walking inflammation, tender all over from the abuses suffered by the McDowell-Franklin bypass operation and by the brutal power plays that installed McDowell and compelled the advance towards Manassas Junction.
These are not the only abuses Scott suffers, but they are emblematic. For example, as Chase was pushing forward the fortunes of McDowell (and Franklin), a parallel sponsorship featured Montgomery Blair's patronage of Ben Butler, also at Scott's expense, with a Scott-Butler feud erupting after Butler's assumption of command at Ft. Monroe. The private Butler-Blair correspondence is possibly the most vibrant, offensive, and shocking Civil War correspondence I myself have seen and I commend it highly to those who have shielded themselves from the political aspects of the ACW.*
The tendencies inherent in the McDowell-Franklin collaboration leave Scott angry enough that when McClellan arrives on the 26th of July and confers with him on the 27th, Scott famously contrives to detain GBM so that he cannot attend a Cabinet meeting to which Lincoln has invited GBM (but not Scott); this is followed by Scott ordering McClellan to ride through the city and collect stragglers, thus keeping him clear of "browsing presidents" and visiting Cabinet secretaries.
Scott, in his way, is asserting lawful command to head off any repeat of McDowell-Franklin. Scott is also attempting to imprint the relationship.
He wins small success at least, for in the weeks after his arrival, as Lincoln and the Cabinet continue to bypass Scott, McClellan repeatedly does the decent, correct thing by engaging Scott on questions of organization, strategy, and operations.
These exchanges end badly, as at least some readers should know. The ACW author who paints Scott's retirement as the result of GBM's personal ambition is clearly unfamiliar with the doctrinal and organizational struggles between the two men and the tenor with which Scott fought his cases. Likewise, the author who implies McClellan's complaint to the conclave of radical congressmen was empty, that Scott was in the way, a hindrance to him, that author has clearly kept himself innocent of the many deep disagreements between McClellan and Scott.
There does come a point in the period before Scott's retirement where GBM stops talking to him entirely but it is a big mistake to view this end state as the steady state.
In reprising and improving McDowell-Franklin, McClellan begins by trying to split the difference between Lincoln's penchant for chaos coupled with the Cabinet's lawless ad hockery and Scott's desire for total (lawful) control of his own sphere.
McClellan had developed a working style under Ohio Governor William Dennison Jr. that combined the best that McDowell-Franklin had to offer civilian leadership but within an orderly military and legal framework. In Ohio, McClellan was both Scott and at the same time he was the anti-Scott - i.e. McDowell-Franklin. In Washington, he could not implement this Dennison style of management until occupying Scott's chair.
Until then, McClellan would inevitably work on the side of the divide McDowell and Franklin created, to the detriment of Scott, though with some advantage to the larger cause.
* These private letters used to be online but I have not seen them on the Web anytime in the last five years. They are not to be confused with these mellow letters. Pointers appreciated.