A microscopic model of liquid crystals, with frustrated dipolar, van der Waals, and benzene-ring steric hindrance interactions, yields reentrant phase diagrams with the sequence nematic\char21{}smectic-${\mathit{A}}_{\mathit{d}\char21{}}$nematic\char21{}smectic-${\mathit{A}}_{1\char21{}}$smectic-C. The Lindemann criterion of melting is adapted to liquid crystals and Monte Carlo simulation is used. The smectic-${\mathit{A}}_{1}$ and -C phases occur in two versions, one pointing to in-plane domain formation. Layer tilting is found to be due to permeation-rotation lock-in. The model yields three types of smectic-C phases distinguished by tilt saturation.