Conflicting rules! The book of Battle says the +5 for a lance charge still applies against great spears and long reaching weapons. However, the rules for a Great Spear say the lance charge bonus is negated by a great spear. I have copied in the text from both books for easy reference.

So, which is right?

The Book of Battle states the following:

Review of the Charge

Horsemen armed with a lance get a +5 to Lance skill when charging. If the lance charge is successful, use the horse’s Damage. Knights with other melee weapons can participate in the charge, and they do get the Charge bonus to their weapon skill (granted by the hurtling ton of horse and man), but do not use their horse’s Damage, or benefit from the other advantages of the lance. Charge does not grant a bonus to the rider’s Damage.

If Defenders bear great spears, halberds or similarly long-reaching weapon the Charge Bonus still applies, and so does the normal combat bonus of +5 for mounted versus foot troops. However, the spearmen do not suffer the normal -5 disadvantage of foot versus mounted.

KAP 5.1 states:

GREAT SPEAR
This skill dictates a character’s use of the great spear (sometimes called a “pike”), a heavy two-handed spear used to strike and stab. A great spear grants a +5 modifier when used by foot soldiers against horsemen (thus negating the footmen’s normal disadvantage). The great spear is long enough that it also negates the +5 lance modifier versus non-lance weapons.

Note, I do not own the Book of Battle, so I can't check if this is so, but I think I remember the same question being asked before...

I think that in the Book of Battle, 'Charge' is actually a unit maneuver that you can do also on foot, and you get the bonus. So the bonus for 'Charge' has nothing to do with the Lance or the Great Spear, but on the fact of a group of men acting as a unit and building up momentum. Hence, the Great Spear doesn't cancel that bonus since it is NOT Lance Charge bonus, as evidenced by your quote about other melee weapons getting the same bonus.

Huh. Now that I read the quote you provided more carefully, it says exactly that. :)

There are two types of modifiers: the first is a +5 for the lance attack, which applies, if the unit charges successfully (the unit must be disengaged for this & the unit commander must win his Battle roll - or the Army commander instead, if it is the first round of the battle).
The second is a +5/-5, which occures, whenever a horseman fights against footman. The knight gets an additional +5, while the footman gets -5. The great spear (which is a long 2 handed weapon for footman) negates the -5 for the footman.

So, the great spear does NOT negate the charge bonus, it negates the disadvantage of foot troops vs mounted.

Lothaire, there is a difference between Battle Charge, which is a mass of men charging together and gaining +5 regardless of weapons, and the normal Combat Option Charge, which is explicitly a Lance charge and gaining +5 for the Lance against non-Lance weapons (apart from the Great Spear). Hence why the Great Spear in regular combat neutralizes the Lance bonus, but not during a Battle Charge. Different situations, that unfortunately bear the same name.

You're right. I missed that combat option for skirmishes, cause i never had a charge within such small fights so far.
That explaines perfectly the assumed rules conflict: The BoB explains the rules for Battle, while the standard rule from the rulebook applies to skirmishes.

I believe, this is one of this cases, in which the rules of a supplement book are replacing the (older) standard rules, if you want to use them. Like the winter-phase ecomomics in the GPC or the BotM may replace the standard, if you want.