The Fedcom Civil War
The superstate of the Federated Commonwealth, an economic and military juggernaut that dominated the Inner Sphere, has fractured into its component states: the Lyran Alliance and the Federated Suns. In this cauldron of war, with other factions taking advantage of the chaos, Mercenaries are often relied on to hold ground, or take key objectives. Your brother may not be trustworthy, but a mercenary is loyal as long as the credits keep flowing.
Many mercenaries use vehicles to expand their firepower and capabilities. Mechs may be the kings of the battlefield, but a wise MechWarrior does not discount the power of conventional assets. With the same weapons, armour and power supplies as Battlemechs, tanks and their cousins remain a deadly threat in any combat zone.