Landau theory predicts that the bcc, spin 1/2 Ising model with nearest‐neighbor ferromagnetic interaction K1and next‐nearest‐neighbor antiferromagnetic interaction K2has a continuous transition with a two component order‐parameter (n = 2) between the paramagnetic and the type two antiferromagnetic phases for K1/K2<3/2. For K1/K2≲3/2, we show that this system has a transition temperature, determined from matching high‐ and low‐temperature free‐energy series, which is well above the temperature at which the susceptibility diverges. This supports the conclusion, also drawn from renormalization group and Monte‐Carlo calculations, that the transition is driven first‐order by fluctuations.