The blue shirts was the name given to the followers of Overton. After several defeats, Overton and the surviving blue shirts went to his small base outside of Front Royal in neutral territory. There was a three way battle when troops from Casanova Ville arrived. Ryan and his loyal troops joined Overton's people and fight them off. After the battle Overton broke his word and tries to kill Ryan. One of Overton's own men cut him down. The wounds were deadly but he survived long enough to get the group wondering how he knew about the mat-trans system. Mildred takes pity on him and gives him poison to end the pain. (Gemini Rising, Gaia's Demise)
Pretty much all the sec men that Silas had put together were finally wiped out between the attacks of hungry mutants and the final battle between Ryan's forces when they attacked. It is possible that a handful survived and escaped. (Dark Reckoning)