| 1965 | U.S. planes begin combat missions over South Vietnam. In June, 23,000 American advisers committed to combat. By end of year over 184,000 troops in area. |
| 1966 | B-52's bomb DMZ, reportedly used by North Vietnam for entry into South. |
| 1967 | South Vietnam National Assembly approves election of Nguyen Van Thieu as president. |
| 1968 | U.S. has almost 525,000 men in Vietnam . In tet offensive, Viet Cong guerrillas attak Saigon, Hue, and some provincial capitals. |
| 1969 | President Nixon announces Vietnam peace offer begins troop withdrawals. |
| 1970 | U.S. troops invade Cambodia in ordet to destory North Vietnamese sanctuaries. |
| 1971 | Congress bars use of combat troops, but not air power, Laos and Cambodia. |
| 1972 | Nixon responds to North vietnamese drive across DMZ by ordering mining of North Vietnam ports and havy bombing of Hanoi-Haiphong area. Nixon orders" Christmas bombing" of North to get North Vietnamese back to conference table. |
| 1973 | President orders halt of offensive operations in North Vietnam. |