The Ready Battalion is back in action. Second Battalion, 6th Marines, out of Camp Lejeune, N.C., has replaced 1st Battalion, 9th Marines, in Afghanistan and is now patrolling Nawa district in central Helmand. Its a mission that will likely be complicated by the Corps’ pending drawdown in Afghanistan — Nawa is one of the next three districts in Helmand in which the security has been identified for transition this spring to Afghan control. The Walking Dead of 1/9 were formally replaced by 2/6 in a ceremony at Forward Operating Base Geronimo late last month, but were still in theater through…