Iraq war: How the year US troops served shaped their fight

"It was an ungodly mess."

This is how US Army veteran Alex Horton describes fighting in Iraq in 2007. The war was in its sixth year, and America had sent in a "surge" of troops to battle Iraqi insurgents.

He fought in some of the war's heaviest combat, but Horton was there for only a fraction of the conflict's overall length.

Ten years after the US-led invasion millions of American veterans carry experiences shaped by the period in which they served in Iraq. What they saw and how they felt during those moments charts the evolution of the war.

The BBC talked to three veterans - one each who served during the invasion, surge, and drawdown - to contrast their experiences.

Reported and edited by the BBC's David Botti

Camera by Peter Murtaugh

Photos/video courtesy: Alex Horton, Brandon Friedman, and Todd Ward