Watch Panorama online: Episode 4 The Battle for Bomb Alley

For four years, thousands of British servicemen fought with the Taliban for the district of Sangin - the most violent part of Afghanistan. The fighting cost 106 British lives, including Staff-Sergeant Olaf Schmidt, who won the George Cross there. Last year, the British withdrew - handing the area over to the US Marines. Ben Anderson, who was with the British forces in 2007, returns to see if the Americans are faring any better. His remarkable film follows Lima Company, a unit of the US Marines, as they dodge improvised bombs and struggle to reclaim the same territory the British previously occupied. As the war enters its tenth year, with Sangin still far from secure, real questions remain as to what so many British men died there for.

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