MICV-65
In the 1960s the United States Army Infantry School at Fort Benning started exploring these concepts on their own initiative. The M113 normally sat its infantry section on either side of the vehicle on benches, facing in towards the center. The School changed this arrangement by relocating the benches to the middle and having the infantry sit back-to-back, facing out. Covered rifle ports were cut into the walls, along with armored vision slots just above them, allowing the infantry to fire while under armor.
This experiment led to the development of the XM734, similar to the Infantry School version with the addition of a centrally mounted one-man enclosed gun cupola equipped with twin MGs or other weapons, and pintles for machine guns that could be fired from the rear of the vehicle though the top hatch. The result was a vehicle with dramatically improved firepower compared to the original M113. Showing promise, the Army decided to formally study new vehicles, forming the MICV-65 program.
The primary concept studied under MICV-65 was a new IFV. Two main proposals were submitted, Pacific Car and Foundry's XM701 based on the M109 and M110 self-propelled artillery, and FMC's XM734 based on the M113. The program eventually selected the XM701 for further work. A requirement for a lighter scout vehicle also started at the same time, accepting two different proposals for the XM800 Armored Reconnaissance Scout Vehicle, one tracked, one wheeled. All of the vehicles were equipped with a similar turret armed with the M139 20 mm cannon (a licensed version of the Hispano-Suiza HS.820) and an M60-derived machine gun on a pintle mount.
FMC continued work on their own in spite of losing the MICV contest, and started work on a private project known as the XM765 Armoured Infantry Fighting Vehicle based on the M113 machinery and generally similar to the XM734 but with thicker armor and sloping it wherever possible. Although the AIFV would go on to see a number of international sales, the Army rejected it for a variety of reasons.
Testing of the XM701 completed in 1966, but the vehicle was eventually rejected as it was too heavy to be airlifted by the C-141 Starlifter that was rapidly becoming the basis for the US Air Forces strategic airlift system.
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