Unless it is engaged in combat, a unit with this special rule must make a 'Stupidity' test during the Start Of Turn sub-phase of its turn. To make a Stupidity test, test against the unit’s Leadership characteristic. If this test is failed, the unit becomes Stupid. A Stupid unit:

• Moves during the Compulsory Moves sub-phase.

• Must move straight ahead, without performing any manoeuvres.

• Cannot march or declare a charge.

A unit or mount that does not have this special rule becomes subject to it when joined or ridden by a character that does (Stupidity is contagious).