The field training of army units includes high financial, material and human resource investments. From this reason, an emphasis on the simulator training of these units arised recently. But the training in simulator needs to have the simulated units as intelligent as a human beings are, so the field training with real human opponents can be successfully replaced with the simulator training. This work deals with the design of fighting unit's intelligent behaviour, that will be applicable in the E-COM simulator environment. Work covers the description of intelligent agents and ways how to achieve their rational and autonomous behaviour. The proposal and the analysis of intelligent fighting unit's implementation and unit's communication with surrounding environment, basic implementation of this proposal and experiments with created implementation are also described in this work.