Not a conventional US Army division. But the US Army's 75th Rangers were in South Vietnam. The 75th had "Ranger" companies strung out in each MR (Military Region I, II, III, and IV/also called I Corps, II Corps, etc.). For example P company (called Papa 75th Rangers) were in I Corps. Kilo 75th (K company) may have been in either II or III Corps, etc.
17th parallel
It would depend on which countries army you are referring to. In the case of the US Army then it is possibly the Vietnam War.
WWII had the AIRBORNE Divisions (Paratroopers) Vietnam had the AIRMOBILE Divisions (Helicopter borne infantrymen) The 1st Air Cav was the US Army's first "Airmobile" division in history, to deploy and enter combat (battle of Ia Drang 1965). There is a movie (film)about it, Mel Gibson's "We Were Soldiers Once..."
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4th division
The US Army's 101st Airborn Division (Ambl).
Division.
It was the result of the 1st Indochina War, aka French Indochina War (1946-1954).
It is actually ARVN meaning Army of the Republic of Vietnam during the Vietnam War.It is actually ARVN meaning Army of the Republic of Vietnam during the Vietnam War.It is actually ARVN meaning Army of the Republic of Vietnam during the Vietnam War.It is actually ARVN meaning Army of the Republic of Vietnam during the Vietnam War.It is actually ARVN meaning Army of the Republic of Vietnam during the Vietnam War.It is actually ARVN meaning Army of the Republic of Vietnam during the Vietnam War.
17th parallel
Generally, the US Marines didn't mark their helmets, as they wore cloth camo covers in all three wars (WWII, Korea, Vietnam). The US Army wore plain steel (sometimes with netting) only in WWII & Korea. In Vietnam, for the first time, the US Army also wore camo cloth covers. In WWII, the US Army (either the unit or the men themselves) painted their "Division" symbols on their helmets. From smallest to largest: Platoon, Company, Battalion, Brigade, Division, Corp, and Army. There are shoulder patches for the Brigade, Division, Corp, and Army. By far, the most common patch is the divisional patch. During the Vietnam War, sometimes the men had their division patch sewn onto their helmet covers.
It would depend on which countries army you are referring to. In the case of the US Army then it is possibly the Vietnam War.
For North Vietnam or South Vietnam? The North Vietnamese were known simply as the 'North Vietnamese Army' (NVA) to US forces, but their actual title was Vietnam Peoples' Army, as it common practice in Communist states. The South Vietnamese Army was referred to as the Army of the Republic of Vietnam (ARVN).
It wasn't divided before the war. The division happened at the end of the war.
WWII had the AIRBORNE Divisions (Paratroopers) Vietnam had the AIRMOBILE Divisions (Helicopter borne infantrymen) The 1st Air Cav was the US Army's first "Airmobile" division in history, to deploy and enter combat (battle of Ia Drang 1965). There is a movie (film)about it, Mel Gibson's "We Were Soldiers Once..."
army division
NVA (North Vietnamese Army).