Rubuta ci gaba don wannan sakin layi - A 1845, Bliss ya shiga cikin sojojin Amurka na Jamhuriyar Texas, kafin a hade shi. Tsakanin Afrilu 1846 da Nuwamba 1847, ya shiga cikin Yaƙin Mexico, gami da yaƙi a yaƙe-yaƙe na Palo Alto
, Resaca de la Palma da kuma Buena Vista. An ba shi izini ga Major a watan Mayu na 1846, kuma ya ba shi izini ga Lieutenant Colonel a watan Fabrairun 1847 don aikin jaruntaka da daraja.