In order to assess the effectiveness of software fault tolerance techniques for enhancing the reliability of practical systems, a major experimental project has been conducted at the University of Newcastle upon Tyne. Techniques were developed for, and applied to, a realistic implementation of a real-time system (a naval command and control system). Reliability data were collected by operating this system in a simulated tactical environment for a variety of action scenarios. This paper provides an overview of the project and presents the results of three phases of experimentation. An analysis of these results shows that use of the software fault tolerance approach yielded a substantial improvement in the reliability of the command and control system.