Advancing troops were not allowed to stop and care for wounded soldiers. All men carried an emergency field-dressing and if possible attempted to treat their own wounds. The wounded soldier then had to wait until the stretcher-bearers arrived. Once the injured soldier had been picked up by the stretcher-bearers, he would be taken to the Regimental Aid Post that was usually based in the reserve trenches. The Regimental Medical Officer and his assistants cleaned the wounds, applied dressings, and gave injections. The injured man was then taken to the Advanced Dressing Station. Wounds were again treated and sometimes emergency amputations took place. The wounded soldier was now moved to the Casualty Clearing Station where surgery, if needed, was carried out. During a major offensive like the Somme.