The North invaded the South and defeated them (conquered them).
North Vietnam conquered South Vietnam and became one nation. The Republic of South Vietnam no longer exists.
The North Vietnamese Army would break the treaty and invaded South Vietnam. South Vietnam quickly fell to North Vietnam, which created one, Socialist Vietnam.
This is the main one- South Vietnam and its supporters were not sufficient enough to defeat Communist North Vietnam, who had the help of China and other Communist countries. So the South was defeated, the North took over the South and combined South and North into one country, Vietnam. Due to the whole country becoming Communist many South Viets fled the country as refugees.
North Vietnam defeated the South (or the North conquered the South).
There no longer is a North Vietnam, North Vietnam and South Vietnam were joined together after the Vietnam War.
South Vietnam's surrender to North Vietnam is what ended the Vietnam War. The North Vietnamese had the goal of Vietnamese Unification and the surrender of South Vietnam in 1975 allowed them to achieve that objective.
Air war over North Vietnam. Ground war in South Vietnam; Riverine war in South Vietnam.
Air war-North Vietnam Ground war-South Vietnam
Then in North and South Vietnam.
North Vietnam=Air War South Vietnam=Ground & Riverine War
Almost half correct but sort of turned around a bit. The Korean War began that way in 1950. The Vietnam war began by infiltration in 1955 (slowly escalating in guerrilla buildup and strength). The Vietnam war ended by a North Vietnamese Army invasion of RVN (Republic of South Vietnam).