  The conflicts between armed groups often go on for years. The classical model
of such conflicts accounts for the number of participants and for the
technology level of the equipment of the groups. Below we extend this model in
order to account for events that are present for limited time. As examples we
discuss three kinds of such events: inclusion of reserves, presence of
epidemics and use of non-conventional weapons. We show that if such events are
not handled properly by the leaders of the groups the corresponding group can
lose the conflict.
