It will decide which narrative will triumph: the dream of the caliphate, or the nation of Iraq.
and the battle will be bloody, with booby traps and mines and civilian casualties.
The press will undoubtbly see these thing, and make the good guys look bad, while they were not there with the casual killing and deliberate atrocities that are occuring now. This will allow the pacifists rewrite the story, as they did in Kuwait (see note below that I added to the Bollywood film Airlift).
the part about this battle being a test to unite the nation is noted:
Liberating Mosul from ISIS genocidaires gives Iraqi Kurds, Shia and Sunni Arabs and other ethnic and religious minorities a common objective. A single "battle forging nationhood" is a romantic notion, but creating a cooperative process to solve a shared problem isn't. The complex political and logistical process of creating, training, deploying and then employing Iraq's diverse forces to drive ISIS from Mosul is a constructive process. In fact, it is a national effort.
it will give this country, artificially forged in the Versaille treaty from the Ottoman empire, a common narrative. This may have implications in the area, and the alternative is a tripartate country of Kurds. Shiites backed by Iran, and Sunnis who hate each other.,
or as Austin Bay notes:
Will Iraqi national unity emerge from this national effort? It could be a significant step to bridging divisions and building trust. The national effort, however, must first deal the apocalyptic fanatics a thorough and uncompromising defeat.