Godzilla, a mutated leviathan born of thermonuclear testing, soon became Tokyo's bane as it approached the hapless metropolis. The Japanese Self Defense Force released its full arsenal, among which included the 155mm Howitzer M1, a modern weapon whose shadow was cast in battles of antiquity. These machines would be the city's first defense against Godzilla, and if this assault were to fail, a barrier of electricity awaited the unsuspecting monster. The howitzer fired its rounds, but this attack proved futile against the nuclear behemoth. The monster marched through the first offensive, and tossed aside the searing cables that stood in his way, effectively rendering the second offensive inoperable. It proved its strength to the world, and it began its long, deadly assault on Tokyo...

Four years following Godzilla's defeat, the howitzers were deployed once more against a similar monster. Varan, an immense reptillian juggernaut, was approaching Tokyo. As plans were concocted to deal with the imminent threat, Varan reached land near the Haneda Airport. Tanks, jets, and the 155mm Howitzers were all launched into battle. They continued to fire on Varan, to no avail. Ultimately, Varan was defeated when it ingested two bombs with a special gunpowder. Though the 155mm Howitzer M1 was of little assistance in the long run, it at least aided in repelling the monster long enough for the final plans to go into effect.