Defaults: IQ-6 or Strategy (any)-6
Tactics (IQ/Hard) is the ability to outguess and outmaneuver the enemy in small-unit or personal combat. (B224)
Martial Arts[]
Abstract Tactics[]
In GURPS Martial Arts page 60 the concept of a Quick Contest endowing optional rerolls to the victor was introduced. This was Abstract as opposed to Mapped.
It is one of the free excerpts: http://www.sjgames.com/gurps/books/martialarts/img/tactics.pdf
Only "leaders" rolled. MoV multiplied by 10% of victor's force to determine number of rerolls for groups of 10+
These were per Battle so how that was defined became important in regard to when they would expire, since new battles meant new contests.
There should probably be some kind of activation time, like 10 seconds, which could be modified via Time Spent penalty or bonus.
Where complications arise is if you have a 3-way war. Can you even do a Quick Contest between 3 people? Even if you get 1 winner, you'd have different margins over the different losers, so would you get that many but only against them?
Technical Grappling[]
One Foe introduced by Douglas Cole in GURPS Martial Arts: Technical Grappling references Abstract Tactics in saying that anyone using One Foe cannot benefit from its rerolls.
This presumably means via the Leader using a Concentrate to give orders.