At the age of nineteen, Richard Coulter enlisted in the Westmoreland Guards in his hometown of Greensburg, Pa. The ranks of the Guards were filled with the sons of the elite families of Westmoreland County, and Coulter was certainly among the elite. His uncle, for instance, had a long record in public service, including stints as mayor of Greensburg, representative in both the state and national congresses, and appointment as Justice of the state Supreme Court. Though his father had died when Richard was barely three, through family connections, he was able to study law at Washington and Jefferson College, and earned entry to the bar when only nineteen. Not long after, the Guards were mustered into the federal service as Company E , 2nd Pennsylvania Infantry Regiment, and sent south to fight in the Mexican War.
Coulter's regiment was involved in several key engagements, including Winfield Scott's capture of Vera Cruz, the battles of Cerro Gordo, Contreras, Churubusco, and Chapultepec, and the capture and occupation of Mexico City. An outgoing man, voluble and educated, Coulter took a dim view of what he saw as immorality and corruption in the army, disapproving of the unscrupulous vanity of John White Geary, and feeling disappointment or disgust at the drunkenness, disorder, and lack of discipline in the ranks.
In June, 1848, the regiment left the capital and were mustered out of the service at Greensburg one month later. Though he left the army, the army never seems to have left Coulter. During the 1850s, he was active in militia units, and when the Civil War broke out, he raised the 11th Pennsylvania Infantry, serving as its colonel for the duration of the war. Know as "Fighting Dick" Coulter was wounded in action three times, rose to Brigadier General, and was brevetted to Major General before returning home. A successful coal mine developer and banker, he died in Greensburg in 1908.