The 60 mm tank cannon wasa special-caliber tank cannon designed to be used on reconnaissance vehicles and light tanks that would serve the United Earth Government's ground forces.
First conceived in the United War Department's Bill of 2219, written the year of the creation of the UEG. The Bill called for all the standard armaments, weapons, tanks etc. that the United Earth Government would then put into mass service. One of the weapons that was to be used by armored vehicles - tracked and wheeled - was the 60 mm cannon, which was to be developed by the age-old armaments company Rheinmetall Defense.
The 60 mm gun was first placed on the Raccoon APC (model M2), able to carry several troops and made to provide close anti-armor support for mechanized infantry. The M2A1 model carried a much lighter but rapid-firing 20 mm cannon, and was able to carry a larger complement of troops. The Raccoon operated for roughly eighty years up until 2295.
Within that time, the 60 mm gun was also installed on a tracked reconnaissance vehicle designated the M5 "Tetrarch", which was fast as it was powerful. It was to "provide short-range reconnaissance to mechanized divisions and units, and to provide on-hand support against enemy armor for mechanized units." Despite it's poor armor, in massed numbers its overwhelming speed and powerful gun allowed it to remain in service for years until 2307.
The next vehicle to use the 60 mm tank cannon was very controvertial. The MCT-A11, designed to be a fast cruiser tank that balanced protection, speed and a powerful armament, was deemed unfit for duty due to it's relatvely thin maximum armor of barely over 3.5 inches. Therefore, the armor was increased roughly two inches. This, despite increasing the protection of the crew, weighed it down considerably, lowering the top speed as well. This was also disapproved by the War Department, who then ordered Bavarian Heavy Engineering, the bureaux that originally designed the MCT-A11, to make changes to the chassis to allow for a more powerful engine. They successfully did this, and despite increasing armor and maintaining a high rate of speed, the interior of the hull had become too cluttered. The 85 mm gun, which had originally replaced the 75 mm version early in the trials of the cruiser tank, had again been replaced by the much older yet reliable 60 mm gun. This version would later be known as the "meat shield", simply because against heavily-armored tanks it would simply absorb cannon fire, being unable to penetrate the tank's thick armor with a small 60 mm gun. This 60 mm version, along with the original 75 mm and final 85 mm versions, would eventually be used during the First War of Continuation, primarily during the Second Battles of Mars and Earth.