The Viet Cong or "Charlie" as they were known by the US forces proved to be a worthy enemy. Throughout the war the local forces continuously harassed the US and free world forces. They soon learnt that the best tactics they could employ were hit and run, ambush and booby traps, all of which they became experts at. The local forces were also able to blend in quickly with the ordinary civilians making it even harder to spot friend from foe. During the Tet Offensive of 1968 the Viet Cong local forces suffer high rates of casualties which took away much of there fighting capabilities. They then switched tactics and started acting as guides leading NVA troops along the Ho Chi Minh trail into the South of the country.