The past history of the robot known as Tank is unknown to everyone, including himself. At some point he became a slave to the Toad, who due to a quirk of nature swapped powers with Magneto and took over Sentinel City. When the Human Torch set up in the Savage Land burned out, Black Bolt and his Iron Avengers went to investigate; they would end up battling with Toad. During the fight, Toad would use his magnetic powers to force Tank to fight Black Bolt.
The battle would end when Iron Maiden and Cable would work together to redistribute the Vibranium beneath the Savage Land, reversing the conditions that caused Magneto and Toad to swap powers. With the Toad defeated and Magneto reinstalled as ruler of Sentinel City, Tank would join the Iron Avengers. He would be seen attacking Absorbing Man when the villain literally absorbed all of New York City.
Tank's whereabouts following the defeat of Absorbing Man remain unrecorded.