In this paper we describe the agent-based modelling component of the CAVALIER (Communication and Activity VisuALIsation for the EnteRprise) tool suite.  CAVALIER also includes techniques based on self organising neural networks and simulated annealing for visualising social networks; and metrics for comparing the efficiency of different organisational structures in processing information.  Our goal is to help create efficient military organisational structures for the 21st century, particularly structures involving international coalitions.
     The modelling component of CAVALIER involves agents arranged in various structures co-operating on some goal.  Our simulations to date have involved a simple "SCUD hunt" scenario, a search-and-respond scenario, and a joint warfare scenario.  Agents have access to a map of the grid-based world including (possibly inaccurate) positional information for both targets and other agents.  Agents also have the ability to plan shortest-part routes to targets, avoiding obstacles. Agents communicate by passing messages to each other including "I am here," "I have found a target" or "I need additional support."
     The simulation framework exploits the object-oriented inheritance properties of Java, by specifying agent behaviours as Java classes.  The reflection properties of Java are exploited by specifying these behavioural classes in a configuration file which is dynamically loaded.
     We believe that, in order to gain understanding of organisational design, it is important to use simple and easily understood testbeds that permit rapid experimentation, in much the same way that early experiments with rapidly-breeding fruit flies led to modern successes in genetic engineering.
     The goal of our modelling work is firstly to validate the organisational metrics we have developed, and secondly to establish under what circumstances certain organisational structures are appropriate.  For
example, in rapidly-changing situations, independently acting agents are most effective, while in less rapidly changing situations with high-quality information available, the quality of coordination becomes most important.
     We are currently extending our work to include cultural factors in international coalitions, using formal modelling of belief structures.