Skirmishers have the following rules:

Skirmish Formation

Skirmishers are deployed in a 'loose' formation, where the models are not placed in base contact, but are positioned roughly 1/2" apart. The models in the unit must still face the same direction and the unit will still have a front, two flanks and a rear – essentially the only difference is that the models are slightly spaced out. This dispersed formation allows Skirmishers to move and shoot with greater freedom than other troop types. All Skirmishers in a unit do not count as blocking each other's Line of Sight (note that they still count as blocking Line of Sight for other units). As long as you can draw a Line of Sight from the front rank to the target, the second and subsequent ranks may fire too.

Skirmishers & Charging

If skirmishers declare a charge (or a charge reaction that does not involve fleeing) they tighten their loose formation into a 'normal' formation after the charge distance is rolled and the chargers are moved. This happens 'for free' at the moment both units move into base contact. The unit immediately forms up in base contact around the centremost model in the front rank (the Skirmishers' controlling player can choose which if the front rank has an even number of models) that is also in base contact with the enemy.

The number of ranks, files and the formation's facing do not alter as the Skirmishers tighten up – all that happens is that models that were previously spaced out are now in base contact with one another. This has the effect of rendering the Skirmishers' loose formation into a regular shape so that other units can fight them in the normal way.

If the Skirmishers are not in base contact with an enemy in the Remaining Moves sub-phase, the controlling player must move them apart so that they readopt their loose formation.

Vanguard

Skirmishers are inevitably at the forefront of any advance – Skirmishers have the Vanguard deployment special rule.

Free Reform

A unit of Skirmishers moves, wheels, marches and charges just like other troops. However, unless it charges, a skirmishing unit is allowed to reform twice during its move; once before they move, and at the end of their move. The unit may do this even if it marches, provided that no model ends up moving a number of inches higher than double its Movement value.

Feigned Flight

A unit of Skirmishers that chooses Flee as a charge reaction does not cause Panic from fleeing through friendly units and may re-roll failed rally tests in its next Compulsory Movement Phase (unless it is forced to Flee again from another source). In addition, it is then also free to move during the remaining moves part of the Movement phase. The unit is also free to shoot as normal (but always counts as having moved). Note that if the flee move of the Skirmishers do not take them beyond the charge reach of their enemies, the unit suffers casualties as normal.

Fire on the March

Skirmishers can shoot even if they marched or reformed earlier in the turn. However, the normal -1 To Hit penalty for moving and shooting still applies.

Light Troops

Skirmishers' natural inclination to a sparse formation makes them much less likely to suffer hits from missile fire – all shots aimed at a unit of two or more Skirmisher models with an individual Unit Strength of 2 or less suffer an additional -1 To Hit penalty. However, skirmishers simply lack the necessary mass to push forward onto the enemy and are easily overwhelmed by troops used to fighting in grinding melee. Skirmishers always counts as having zero ranks, and therefore cannot claim a rank bonus or be Steadfast (unless they are also Stubborn).

Characters

A character model that joins a unit of Skirmishers gains the Skirmishers special rule as long as they stay with the unit. Characters may only join Skirmishers with the same troop type (explained in the Troop Types chapter) as them.