Green: Enter without explosives or firing unless enemy targets are identified.

Amber: Enter firing. No explosive entry.

Red: Explosive entry using a grenade or charge. Enter firing at will.

What happened in Helmand's Sangin Valley in the spring of 2007 was nothing short of extraordinary. After the last gasp defence of the platoon houses by the Paras that preceded them in theatre, the soldiers of the Royal Anglian Regiment arrived in Afghanistan charged with taking the battle to the enemy. Despite brutal, debilitating conditions, the tour that followed became a bloody lesson in how to conduct offensive infantry warfare. Over a six-month tour of duty, the 'Vikings' battlegroup unleashed hell in heavy, relentless fighting that saw teenage soldiers battle toe to toe against hardcore Al Qaeda and Taliban warriors at unprecedented levels of ferocity.