We present results from phase-field simulations of a two-dimensional model of dislocation microstructure development under increasing strain that incorporates the effects of the full, three-dimensional, microstructure in an approximate way. Despite its simplicity, the model yields quantitative predictions of both the deformation properties of face-centered cubic metals as well as key descriptors of the evolving microstructure over a wide range of stress and strain. The present results have important implications for how we interpret and describe the deformation properties of fcc materials.