Large two-dimensional lattices of interacting magnetic dipoles representing thin films of amorphous rare-earth–transition-metal alloys are studied on the Connection Machine. The accuracy of the results is established by comparing the simulated dynamics of isolated Bloch walls with theoretical predictions. The effects of random axis anisotropy on the process of magnetization reversal are then investigated, and the nucleation and growth of reverse-magnetized domains are found to be the mechanism of reversal. The obtained hysteresis loops have very high squareness, and sample coercivities are well within the range of experimental values.