you all think that mamoths are great machines, well they are(when they are supporting your troops not when they leading a battle or caught in a one on one battle against Nod tanks.

what makes the Mamoth tank so fiersum is not it's fire power alone(although it is pretty powerful) but the fact that if one is around there are usually medium tanks and engies backing it up.
if you go it alone in a mamoth tank then you deserve to lose it.

it should be right behind your main force at all times. while your medium tanks and hum-vees are attacking use it to take out important targets. in other words USE IT TO DESTROY THE IMPORTANT ENEMY TANKS OR TO SCARE THEM.
by the time your mamoths are engaged the nod tanks should be pretty busy, allowing the slow turning of the mamoths to attack.

conclusion- don't use Mamoths to lead the assault use them to be the 10 ton weight that breaks the cammel's back(or in this case Nod's )