The walking siege engines of the Cosmic Era
The Rocky Mountain Republic owes in large it's existence to a single limited run of primitive mechs, the Assault/Bombard Mech model 1.
T'was a great roar, milord, and the ground was rent and the horses took their bits in their teeth and there was much confusion. No magic could reach so far, and none of our magehounds scented wizards. We do not know the deviltry of the enemy, and for this we lost the battle.
As they travel they notice a horrible rotten smell. As they travel it gets stronger and stronger forcing them to cover their noses and mouth less they choke on the horrible smell. Rotting animal carcass that has been ripped apart and tracks all over, covered in maggots.