As you went from assignment to assignment in the Army of my day, the officially sanctioned nicknames of companies repeated endlessly: Charlie Company was always Chargin' for instance. It got a little better at battalion level, where the peculiar nickname of a regiment (a formation long absent from Army rosters) attached to its surviving battalions. There was no mistaking Buffalo for Tomahawk or Manchu.
As you now drive the country, you notice the self-applied nicknames of FM radio stations repeat endlessly and meaninglessly: the River, the Eagle, the Rock, Easy.
So we know from life that names repeat and we would laugh at anyone stepping forward to claim to be from the "original" Chargin' Charlie Company or the first staion to call itself "Easy" one-oh-something.
As history readers, however, we are very fond of "the," as well as "the first." The success of a pop history author like Alan T. Nolan with a single subject, "the" Iron Brigade, can corrupt truth simply through his own success and our expectations of originality and uniqueness. I was reminded of this when author Timothy Reese pointed me toward an article by Tom Clemens called, "Will the Real iron Brigade Please Stand Up."
Nolan did not pretend that his Iron Brigade was the only one in the Civil War, but his commercial success ensures that we associate "Iron Brigade" with black hats and Westerners. The effect is that of his success corrupting our memory and judgement. Not a fair deal, that.
Clemens points out a number of units adopting the "Iron Brigade" moniker - I read the article twice and still lost track of the total. And here is a website boosting the "real" Iron Brigade (claimed for a New York outfit described by Clemens) based on precedence. Reading Clemens, we understand that claims of a"first" Iron Brigade can be difficult to establish, if that's what makes a nickname "real."
It is not just Nolan's success that has corrupted us. Consider "the" ironclads (Monitor and Virginia), "the" baloonist (Thaddeus Lowe), "the" Civil War sub (Hunley) and "the" end of the war. All are false constructs, as listed here.
"The Antietam campaign," the whole phrase, is an atrocity born of commerical success, as Reese might point out himself.
You might even consider "the" South and "the" Union as worth further inspection.
If we shake off other people's success, details start to reveal themselves and history is in those details. Certainly, my own enjoyment of it is.