Utilizing the Time Warp Operating System, the CTLS project at JPL has produced a distributed combat simulation called STB-87 and measured its performance on the JPL Mark III Hypercube. By applying the spiral model of software development, the CTLS project will produce a series of software test beds, to culminate in the completion of a working prototype theater level simulation three to five years hence. STB-87, the first software test bed, is a ground-based combat simulation decomposed into objects which communicate via time-stamped messages. The use of incremental object-based design, coding, and testing has been helpful when developing a parallel simulation. The performance measurements show that, with the appropriate choice of object granularity, STB-87 is able to achieve a speedup factor of 12 running on a 32-node Mark III Hypercube.