Before the first shot was fired, the battle was already being won — or lost — in training.

In this opening episode of "The Debrief," Lt. Col. (Ret.) Scott Rutter and Matt Paul, authors of "Damn Fine Soldiers," go back to the beginning. As commander of Task Force 2-7 Infantry, the legendary "Cottonbalers," Rutter led 900 soldiers on a 21-day advance from Kuwait to Baghdad in 2003. Paul was one of his captains. Together, they're telling the full story for the first time.

Episode 1 of the "21 Days to Baghdad: Lessons in Modern War" series covers everything that came before the fight: rebuilding readiness after the 1990s defense drawdown, grueling live-fire training at Fort Stewart, a pivotal National Training Center rotation just months before deployment and the last-minute fielding of new digital systems in the Kuwaiti desert. They also reflect on what it meant to carry the 200-year legacy of the Cottonbalers into combat.

With wars once again reshaping the global security landscape, the lessons from America's last large-scale combat operation have never been more relevant.

This is a leadership story.

In this episode:

• How 9/11 transformed a peacetime Army overnight
• Training soldiers and families for the fight ahead
• What the National Training Center really teaches
• Fielding new technology days before combat
• Why large-scale combat operations demand a fundamentally different Army