Complex sentence: From 1963 to the end of the Vietnam war in 1975 became gradually the common smoke of marijuana among U.S soldiers in non combat situation and increased heroin addiction among US military personnel a major issue for the U.S Army and the U.S Marines.
Split into simpler sentences: From 1963 to the end of the Vietnam war in 1975 marijuana usage became common among U.S soldiers in non combat situations. Increased heroin addiction among US military personnel became a major issue for the U.S Army and the U.S Marines.