On October 16, the Iraqi government officially declared that offensive operations to retake the city of Mosul have officially begun. The announcement was a political statement signaling moral determination, akin to saying “the die is cast.”

Since the official government announcement, several Iraqi military leaders have attempted to curb expectations of quick victory. One Iraqi Kurd general said the battle could take two months. ISIS says Mosul is the capital of its Caliphate and ISIS fighters will defend it to the last.

Mosul is a case study of what military planners call “battlefield shaping operations.” Battles fought to improve the prospects of subsequent battles are “kinetic” shaping operations. Attacking enemy supply lines shapes operations. The allied air strikes on German supply lines in Western Europe prior to D-Day deprived German ground units of ammo and gas.

Many planners interpret the term broadly. Tailoring supplies for a specific battle is a shaping operation. Gathering intelligence is always a shaping operation.

Strengthening political relations could be a vital shaping operation. I think that applies to Mosul. Bucking up Iraq’s fragile coalition government and reducing friction between the Baghdad government and the Iraqi Kurdistan regional government were definitely a political “shaping” operations pursued by the U.S. and its anti-ISIS coalition.

Military operations to drive ISIS from Mosul began in January 2015. They were not decisive battles — not The Battle for Mosul — but they were preparatory battles fought with the ultimate goal of re-taking the city.

Iraqi Kurdish peshmerga militiamen fought those first battles. They drove ISIS fighters from several small villages to the north and west of Mosul. In the process they cut an ISIS supply line between Mosul and Syria.

The Iraqi and U.S. governments indicated that the Iraqi Army would launch an offensive in April 2015 to take Mosul. In March 2015, the Iraqi Army, en route to Mosul, attacked the city of Tikrit. Tikrit was a slow battle of blood and rubble — house to house fighting, air strikes and suicide bomb attacks. The Iraqi Army took Tikrit in early April.

ISIS decided to defend Mosul with an offensive. ISIS fighters seized the city of Ramadi in May 2015. ISIS hoped the offensive would send the message that the Iraqi Army’s expensive victory in Tikrit settled nothing. ISIS could strike at will. ISIS commanders thought they might once again shatter Iraqi Army morale and damage the political coalition.

Baghdad and Washington decided that ISIS had to be driven from Iraq’s Anbar province (west of Baghdad). The Iraqi Army attacked Ramadi in Fall 2015. It wouldn’t gain full control of Ramadi until early 2016. Ramadi was a ruin. The Iraqi Army fought another slow battle in Fallujah, finally clearing the badly damaged city in May 2016.

Mosul, however, was never quite on the backburner. Allied air strikes, Kurdish and Iraqi Army operations continued. Cutting off ISIS supplies was one goal. Securing positions for the drive into Mosul was another. U.S. and other anti-ISIS coalition members began supplying more than airpower. Boots hit the ground. Artillery units and the infantry to protect them joined advisers and communications experts.

Ramadi and Fallujah were not training exercises, they were difficult battles. However, Iraqi commanders and coalition advisers used these battles to hone the urban combat skills taking Mosul will require. Yes, combat experience — turning volunteers into veterans — is a shaping operation.

Over the past three months, some of the Iraqi Army units that were deployed in Anbar and units stationed elsewhere in the country moved into positions near Mosul — positions secured by prior battles.

The Iraqi government wants to minimize civilian casualties. Mosul’s civilians are Iraqi citizens.

ISIS fighters, however, have seeded Mosul with booby traps and mines. ISIS always uses civilians as “human shields” — hostages.

Though the Battle of Mosul does not have a set timetable, it does have a definite objective: liberating the city from the apocalyptic tyranny of ISIS.

Austin Bay is a syndicated columnist and author.