The Mammoth is armed with two 120mm cannon and twin anti-infantry and anti-aircraft Mammoth Tusk missile pods. An atomic generator powers the enormous vehicle. Mammoths are also equipped to independently carry out limited battlefield repairs.
During the First Tiberium War the Brotherhood of Nod discovered a GDI facility near Mzuzu, Tanzania helping to develop the Mammoth tank. Nod destroyed the factory and its Mammoth prototypes to stall production, delaying the arrival of the tanks on the battlefield. However, they did not succeed fully and these lumbering beasts managed to aid GDI in their final campaign against Nod.
A number of Mammoth tanks were available to captain Nick Parker during his final tour of duty. They'd prove themselves to be effective against all targets encountered during the course of his missions.
As a response to the Mammoth losing its superiority over the years (due to advances in technology), GDI researched and developed its walking successor - the Mammoth Mk. II. Once the walker technology was abandoned GDI revisited the idea of Mammoth tanks and designed the Mammoth Mk. III.
At least one abandoned unit was used by the GDI as target practice for the prototype Mammoth Mk. II at their United Kingdom facility.
The Forgotten managed to acquire some units for their own use. Others were abandoned with surplus field bases; some of these abandoned vehicles were still serviceable by the Second Tiberium War.
In Command & Conquer: Renegade, they continues to be a behemoth dominating the battlefield, with rockets effective against both land and air targets (though the latter requires a lot more practice) and enough armour to withstand severe damage.