The NACM's British Mark IV, Serial Number 4633, is the oldest example of a tank in the US.

She originally entered service with Royal Tank Regiment, though almost nothing is known of her British service. Mark IVs were often used as training tanks to free up the newer Mark Vs for front line duties; and 4633 was sent with several other Mark IVs (4616, 4624, 4629, 4630, 4634, 4636, 4639, 4642, 4646) to America to serve as training vehicles of the Tank Corps, National Army (the stateside Army's tank command). This is noted by the war records of the US 301st Heavy Tank Battalion at the time they trained at Bovington. The 301st also noted that while the Mk.IVs provided good experience in general tank operation and weapons training, the IV and V were completely different beasts when it came to operation and maintenance. The Mark IV required three crew members to drive and steer, while the V only required a single driver.

The vehicles arrived in America on 05 November 1918, less than a week before the Armistice. Several of the Mark IVs, including 4633, were used in Liberty War Bond Drives. At some point during this service 4633 was given the nickname 'Liberty' (not to be confused with the subsequent Mark VIII Liberty tank), though there is some evidence suggesting that multiple tanks received the same name as part of the bond drive efforts. Like the earlier "Britannia", "Liberty" would demonstrate the capabilities of tanks to the public, sometimes culminating in the crushing of a car.

For a while, 4633 was believed to be the actual "Britannia" which was an earlier Mark IV, but photographic evidence and the serial number prove otherwise. Eventually, the AEF Tank Corps returned to the states, and all tank operations were consolidated under the Office of the Director of the Tank Corps at Camp Meade, Maryland. Photos from 1919 and 1920 suggest the Mark IVs were still used for training but were phased out by the Mark Vs brought back from Europe as well as the Mark VIIIs as they were produced.
4633 would luckily survive the WWI scrap drives and go on display at Aberdeen Proving Grounds. Unfortunately she would spend most of her time on display outdoors. The worst damage is from ice, as water would get into small opening in the relatively brittle steel and expand upon freezing, cranking the armor plating. In the fall of 2015, she was turned over to the National Armor and Cavalry Museum at Fort Benning, where she now resides indoors beside the only other WWI-era heavy tanks in the US, the Mark V* and Mark VIII.

Text and photos by Rob Cogan