Infantry Battalion ca. 1965-66
Battalion HQ and Support Company (including 2 57mm recoilless rifles and 2 81mm mortars) and three rifle companies.
Rifle company (113 personnel, in HQ, heavy weapons platoon, and 3 rifle platoons. Heavy weapons totaled 2 3.5" rocket launchers in company HQ, and 2 MMG and 2 60mm mortars in heavy weapons platoon).
This reflects a nominal effective total 400-450 personnel against earlier TOE of 714 (200 in each rifle company).
On 31 May 1965, infantry battalions had an authorized strength of 714 personnel, an average assigned strength of 557 personnel, and an average present for operations strength of 376.
Ranger Battalion [1965-67]
HQ and HQ Company (87 personnel) and four ranger companies (143 personnel each).
Battalion aggregate 659 personnel. Equipment shown included 2 recoilless rifles, no mortars, 10 LMG. Vehicles totaled 11 jeeps and 7 trucks.
On 31 May 1965, a Ranger battalion had an authorized strength of 646, an average assigned strength of 532, and an average present for operations strength of 384.
Ranger Group [1968-72]
Group HQ (213 personnel), recon company (111 personnel), transportation company (114 personnel), engineer company (122 personnel), and three rangers battalions (745 personnel each).
Group aggregate was 2795 personnel. Heavy weapons included 25 mortars and 46 machine guns. Motor vehicles for the group totaled 75 jeeps (8 ambulances) and 24 trucks.
On 31 May 1965, Airborne battalions had an authorized strength of 889, an average assigned strength of 795, and an average present for operations strength of 496. Marine battalions had an authorized strength of 931 personnel, an average assigned strength of 969, and an average present for operations strength of 634.
In calendar 1966, infantry battalions of all types (including ranger, airborne, and marine) averaged 449 personnel present for operations. It was an ongoing MACV goal to increase the operational strength of battalions.
The Marine battalions in 1972 had an authorized strength of 875 (163 in HQ and service company and 178 in each of four infantry companies).
Armored Cavalry Regiments
In 1956, an armored cavalry regiment [battalion] had a squadron [company] of M24 light tanks and two recon squadrons, with M8 armored cars, M3 half-tracks and M3 scout cars. By late 1964 all were reorganized with the light tank squadron, an M8 armored car squadron, a squadron of M114 recon vehicles, and two squadrons of M113’s (organized much like a US mechanized infantry company; each included 3 81mm mortars and a 57mm recoilless rifle, carried in the APCs).
The M114’s were judged unsuccessful, and entirely replaced with M113s Apr-Nov 1964.
After Dec 1964, each regiment gained four M132 flamethrower vehicles (variant of M113).
M41 light tanks began replacing the M24’s from Jan 1965 [five squadrons by the end of 1965, the rest later].
In May 1965 2nd Armored Cavalry was given a troop of four M106 mortar carriers (4.2"); the test resulted in the proposal to establish one troop in each regiment.
There were some plans in 1965 to replace the M8’s with V-100 armored cars. By 1967, each regiment HQ had a troop [platoon] with V-100 armored cars.
In the summer of 1967, the armored car squadrons were disbanded and the M113 squadrons reorganized from 15 to 22 (achieved by cutting the crew size in each APC); M125A1 mortar carriers (81mm) replaced the ground-mounted 81mm mortars that had been carried in APCs.
Thus, it would appear that a 1967 armored cavalry regiment had a HQ (with 4 M106 mortar carriers (4.2"), 4 M132 flamethrower APC’s, and a troop [5?] of V-100 armored cars; light tank squadron (17? M41 tanks); and three mechanized squadrons (each 22 M113 APCs, 3 M125 mortar carriers (81mm)).
20th Tank Regiment
Formed with three companies M48A3 tanks [17 each?] and a mechanized company with 270 men in APCs that was divided with 90 men allotted to each tank company for protection and support.