W. S. Johnson's total synthesis of the sesquiterpenoid longifolene is a classic example of the powerof cationic polycyclizations for constructing complex molecular architectures. Herein we revisit thekey polycyclization step of this synthesis using hybrid Hartree−Fock/density functional theorycalculations and validate the feasibility of Johnson's proposed mechanism. We also exploreperturbations to the 3-center 2-electron bonding array in a key intermediate that result fromchanging the polycyclic framework in which it is embedded.