A reader writes to say that authors referring to Johnston's Army of the Potomac as the Army of Northern Virginia get his goat.
Drew Wagenhoffer also writes to say that "McClellan restored to command" does it for him, McClellan not having been removed from command. Sears, for one, takes a little care here, offering the formula, "McClellan's command was restored to him."
I have a different view of this. McClellan was assigned an entirely new command, the defenses of Washington. His adjunct mission, while commander of the defenses of Washington, was to organize a (**A**) field army to intercept Lee. The fact that a field army was organized and later received the old name "Army of the Potomac" is an accident of history ... especially given that it was John Pope who was named commander of this field army (by city defenses commander George McClellan) on September 5, 1862.
This is going to be surprising if you have digested the formula "Pope was removed from command and McClellan was restored." That statement is as (un)true for 1862 as is "McDowell was removed from command to be replaced by McClellan" for 1861.
You can reach a level of generalization in writing history, where it becomes sludgy.