Doing recruiting services after the end of the campaign Ruggles and the 5th Infantry joined Gen. Winfield Scott's army for the Mexico City Campaign, fighting at Vera Cruz, San Antonio, Churubusco, Molino del Rey, Chapultepec and Mexico City. Ruggles was breveted "for Gallant and Meritorious Conduct" to Major after Churubusco and to Lieutenant Colonel after Chapultepec.