Vehicles don't fight in close combat as such, although they can be attacked by enemy troops. However, heavy vehicles like tanks can break through enemy positions, scattering units and possibly forcing them to fall back – this kind of attack is called Tank Shock and is described below. Dreadnoughts, giant humanoid walking machines designed to spearhead assaults, and other walkers fight in close combat the same way as troops do — see Walkers in an Assault.
Skimmers
These can always choose to move over enemy troops and this neither impedes their movement nor harms the troops below. Enemy troops can attack skimmers in the Assault phase, as close combat takes into account close range shooting and grenade lobbing as well as actual hand-to-hand combat.
Skimmer tanks can still choose to overrun an enemy unit and inflict Tank Shock in the normal manner.
Tank Shock
Tanks can overrun enemy troops during their Movement phase. Having some monstrous metal behemoth coming straight at you is unnerving for anybody!
During their Movement phase, a player can declare that a tank is going to attempt to overrun an enemy unit. If the tank has sufficient movement to get into contact with the unit, the enemy must take a Morale check.
To use Tank Shock, declare which enemy unit or units you are driving at with which of your tanks, and how fast each is moving. To do this you specify a direction and a speed before moving – you may not change direction during this move. Next, measure to see if any models from the unit will be reached by the tank. If the tank reaches the unit it must take a Morale check.
If they fail the check, the unit falls back 2D6" – individual models are allowed to be moved out of the path of the vehicle if they would otherwise end up underneath it. The unit can check to see if it is able to regroup in its own turn as normal, but troops will not be allowed to regroup if there is an enemy unit within 6" (such as the tank that forced them to fall back!).
If a unit is moved over by a tank and it passes its Morale check, individual models can be moved out of the way if they would end up underneath it, but otherwise the unit is unharmed. The troops are assumed to move out of the way and resume their positions as the tank passes. Remember that vehicles cannot move over friendly troops, or over vehicles or wrecks from either side (unless it can push a wreck aside – see the rules for wrecked vehicles under Damage Rolls & Damage Tables).
Death or Glory!
If a unit passes its Morale check against Tank Shock, any troopers from the unit who are in the vehicle's path can stand and attempt to destroy it, rather than move out of the way. This is potentially a rather suicidal thing to do! Each model nominated for this heroic duty gets one attack at the tank as it heads towards him. The attack can be a single shot (one shot, even if Assault 4) from a weapon carried by the model or a single close combat attack using any weapon carried, including krak grenades and melta bombs. The attack hits automatically – resolve the hit against the tank's Front Armour immediately. Then, unless the attack has destroyed or immobilised the tank, the Death or Glory boy is crushed to death by the tank grinding over him – the model is killed regardless of Wounds or Armour (Invulnerable or not!). A crew stunned or shaken result has no effect in this case.