4th Tank Battalion (4th Tanks) is an armored battalion of the United States Marine Corps Reserve. Their primary weapon system is the M1A1 Abrams main battle tank and they are part of the 4th Marine Division and Marine Forces Reserve. The unit headquarters is at the Navy and Marine Corps Reserve Center San Diego, California, but other units in the battalion are located throughout the United States. Until the decision to divest the Marine Corps' armor capability, 4th Tank Battalion was the largest tank battalion in the US military with six lettered companies and an H&S Company. Insignia The coat of arms of the 4th Tank Battalion consists of a green jousting shield bordered gold with two bendlets of gold each bearing a riband of scarlet. It is charged with a gold tank icon, initially the M5 Stuart and later the M1A1 Abrams, behind the insignia of the Fourth Marine Division with a U.S. Marine Corps emblem of silver and gold in the shields upper left. The crest of a U.S. Marine Corps emblem of silver and gold above a wreath (or heraldic torse) of gold and scarlet is above the shield. A gold banner inscribed "Fourth Tank Bn" appears above the arms and another below the arms inscribed "53 Days" in scarlet. The jousting shield is a unique device of the mounted and armored warrior, designed with its upper corners cut away so the warrior could better wield his weapons. Green is the color of armor, while scarlet and gold are the colors of the Marine Corps. The bendlets and ribands are diminutives of the heraldic bend, which is the symbol of cavalry, from which tank battalions descend. The M5 Stuart tank was the first tank used by the battalion in combat, and the battalion was the only Marine tank battalion to use the M5 Stuart tank in offensive operations. (However, Marine defense battalions did use it.) The motto of "53 Days" recalls the battalion being deployed into combat during the Korean conflict's Inchon landings in September 1950, fifty-three days after activation from reserve status. This coat of arms is derived from designs found in Marine Corps files from at least the 1970s. Variations of this design exist, typically substituting the "tank-de-jour" for the original M5 tank. In October 1995, this version of the coat of arms (with M5 Stuart tank) received official endorsement from the Battalion Commander, Lt.Col.