SUSSEX, Wis. - A decade later, the pain of loss still stings. It was 10 years ago that the brutal reality of their wartime mission became clear for the 1st Battalion, 121st Field Artillery. That was when Cpl. Stephen Castner was killed by a roadside bomb near Tallil, Iraq on his very first convoy escort mission.Sunday, new Soldiers in that unit who did not experience that harsh lesson joined others who did for a ceremony commemorating the 10-year anniversary of Castner’s death by naming their Sussex armory drill hall in Castner’s honor